(§§ 226-240.)
226. _Universal Marine Distribution._--Radiolaria occur in all the seas of
the world, in all climatic zones and at all depths. Probably under normal
conditions they always float freely in the water, whether their usual
position be at the surface (pelagic), or at a certain depth (zonarial), or
near to the bottom of the sea (abyssal). This appears both from numerous
direct observations, as well as from conclusions which may be drawn from
their organisation (and especially their promorphology) regarding their
floating life (compare §§ 40-50, 219, 220). Hitherto no observation has
been recorded, which justifies the assumption that Radiolaria live anywhere
upon the bottom of the sea (on stones, Algæ, or other firm substances),
either sessile or creeping. They perform the latter action, however, when
they fall accidentally upon a firm basis or are accidentally placed upon
it, but they seem normally always to float freely in the water with
pseudopodia radiating in all directions. Active free-swimming movements are
only met with in the case of the flagellate zoospores (§ 142). The
development of Radiolaria in large masses is very remarkable (see note A),
and in many parts of the ocean is so great that they play an important part
in the economy of marine life, especially as food for other pelagic and
abyssal animals (see note B). Medium salinity of the water seems to be most
favourable to their development in masses, although it is not unknown in
seas of high and low salinity (see note C). There are no Radiolaria in
fresh water (see note D).
A. The development of Radiolaria takes place in many parts of the ocean
in astonishingly large masses on the surface, in different strata, and
near the bottom. The #Collodaria# (and especially the Sphærozoida) often
cover the surface of the sea in millions, and form a shining layer,
phosphorescent in the dark like the _Noctilucæ_, as I observed in 1859 in
the Strait of Messina, in 1866 at the Canaries, and in 1881 in the Indian
Ocean. Similar masses of _Sphærozoum_ and _Acanthometron_ were seen by
Johannes Müller on the French and Ligurian coasts (L. N. 12), and John
Murray found another in the Gulf Stream, off the Færöe Islands, from the
surface to a depth of 600 fathoms; considerable masses of large PHÆODARIA
live there also.
B. The alimentary canal of Medusæ, Salpæ, Crustacea, Pteropoda, and many
other pelagic animals is a rich field for the discovery of Radiolaria,
and many of the species hereinafter described are from such sources.
Fossil coprolites too (_e.g._, those from the Jura) often contain many
Polycystina.
C. Some ACANTHARIA (#Acanthometra#) and PHÆODARIA (species of _Mesocena_
and _Dictyocha_) {cxlvii}live in the Baltic; I found their skeletons in
the alimentary canal of _Aurelia_, Ascidians and Copepods.
D. The so-called "fresh-water Radiolaria," which have been described by
Focke, Greeff, Grenacher and others, are all Heliozoa, without either
central capsule or calymma.
227. _Local distribution._--As regards their local distribution and its
boundaries the Radiolaria show in general the same relations as other
pelagic animals. Since they are only to a very slight extent, if at all,
capable of active horizontal locomotion, the dispersion of the different
species from their point of development (or "centre of creation") is
dependent upon oceanic currents, the play of winds and waves and all the
accidental causes which influence the transport of pelagic animals in
general. These passive migrations are here, however, as always, of the
greatest significance, and bring about the wide distribution of individual
species in a far higher degree than any active wanderings could do. Any one
who has ever followed a stream of pelagic animals for hours and seen how
millions of creatures closely packed together are in a short time carried
along for miles by such a current, will be in no danger of underestimating
the enormous importance of marine currents in the passive migration of the
fauna of the sea. Such constant currents may, however, be recognised both
near the bottom of the sea and at various depths, as well as at the
surface, and are therefore of just as much significance for the abyssal and
zonarial as for the pelagic Radiolaria. It is easy to explain by this means
how it is that so many animals of this class (probably indeed the great
majority) have a wide range of distribution. The number of _cosmopolitan_
species which live in the Pacific, Atlantic and Indian Oceans is already
relatively large. In each of these three great ocean basins, too, many
species show a wide distribution. On the other hand, there are very many
species which are hitherto known only from one locality, and probably many
small local faunas exist, characterised by the special development of
particular groups. The observations which we at present possess are too
incomplete, and the rich material of the Challenger is too incompletely
worked out, to enable any definite conclusions to be drawn regarding the
local distribution of Radiolaria.
The statements made in the systematic portion of this Report regarding
the distribution of the Challenger Radiolaria are very incomplete. In
most cases only one locality is mentioned, and that is the station (§
240) in the preparations or bottom deposit from which I first found the
species in question. Afterwards I often found the same species again in
one or more additional stations (not seldom in numerous preparations both
from the Pacific and Atlantic), without the possibility of adding them to
the habitat recorded under the description. The necessary accurate
determination and identification of the species (measuring the different
dimensions, counting the pores, &c.), would have occupied too much time,
and the writing of this extensive Report would have lasted not ten but
twenty or thirty years.
228. _Horizontal Distribution._--From the extensive collections of the
Challenger and from the other collections which have furnished a welcome
supplement to them, it appears {cxlviii}that Radiolaria are distributed
throughout all seas without distinction of zones and physical conditions,
even though these latter may be the cause of differences in their
qualitative and quantitative development. In the case of the Radiolaria as
well as of many other classes of animals, the law holds good that the
richest development of forms and the greatest number of species occurs
between the tropics, whilst the frigid zones (both Arctic and Antarctic)
exhibit great masses of individuals, but relatively few genera and species
(see note A). In the Challenger collection the greatest abundance of
species of Radiolaria is exhibited by those preparations which were
collected at low latitudes in the immediate neighbourhood of the equator;
this is true both of the Atlantic (Stations 346 to 349) and of the Pacific
(Stations 266 to 274); in the former the richest of all is Station 347
(lat. 0° 15' S.), in the latter Station 271 (lat. 0° 33' S.) (see note B).
From the tropics the abundance of species seems to diminish regularly
towards the poles, and more rapidly in the northern than in the southern
hemisphere; the latter also appears, considered as a whole, to possess more
species than the former. A limit to the life of the Radiolaria towards the
poles has not yet been found; the expeditions towards the North Pole (see
note C), like those towards the South (see note D), have obtained
bottom-deposits and ice enclosures which contained Radiolaria; in some of
the most northerly and most southerly positions which were reached the
number of Radiolaria enclosed in the ice was relatively great.
A. The greater abundance of Radiolaria in the tropical seas is probably
to be explained by the more favourable conditions of existence, and in
particular the larger quantity of nutritive material (especially of
decayed animals) and not by the higher temperature of the surface, for at
depths of from 2000 to 3000 fathoms where the abyssal Radiolaria live,
the temperature is but little above the freezing point or even below it
(compare the bottom temperatures in the list of Challenger Stations, §
240).
B. Station 271 of the Challenger Expedition, situated almost on the
equator in the Mid Pacific (lat. 0° 33' S.), exceeds all other parts of
the earth, hitherto known, in respect of its wealth in Radiolaria, and
this is true of the pelagic as well as of the zonarial and abyssal forms.
In the Station List the deposit at this point is stated to be
"Globigerina ooze"; but after the calcareous matter has been removed by
means of acid, the purest Radiolarian ooze remains, rich in varied and
remarkable species. More than one hundred new species have been described
from this Station alone.
C. Regarding the Arctic Radiolaria compare the contributions of Ehrenberg
(L. N. 24, pp. 138, 139, 195) and Brady on the English North Polar
Expedition, 1875-76 (Ann. and Mag. Nat. Hist., 1878, vol. i. pp. 425,
437).
D. Regarding the Antarctic Radiolaria, compare § 230, note A, and
Ehrenberg, Mikrogeologie (L. N. 6, Taf. xxxv., A.), also L. N. 24, pp.
136-139.
229. _Fauna of the Pacific Ocean._--From the splendid discoveries of the
Challenger, and the supplementary observations obtained from other sources,
the Pacific seems to be the ocean basin which is richest both
quantitatively and qualitatively in Radiolarian life, {cxlix}excelling both
the Indian and Atlantic Oceans in this respect. It may be assumed with
great probability that by far the largest portion of the Pacific has a
depth of between 2000 and 3000 fathoms, and that its bottom is covered
either with Radiolarian ooze (§ 237) or with a red clay (§ 239), which
contains many SPUMELLARIA and NASSELLARIA, and has probably been derived
for a great part from broken down and metamorphosed Radiolarian ooze (see
note A). Pure Radiolarian ooze was found by the Challenger eastwards in the
Central Pacific (over a wide area between lat. 12° N. and 12° S., Stations
265 to 274), and also westwards in the latitude of the Philippines, twenty
degrees to the east of them (between lat. 5° N. and 15° N.). The great
abundance of Radiolaria present in the neighbourhood of the Philippines and
in the Sunda Sea was already known from other investigations (note B). The
red clay also, which covers a great part of the bottom of the North
Pacific, and which was obtained of very constant composition by the
Challenger between lat. 35° N. and 38° N., from Japan to the meridian of
Honolulu (from long. 144° E. to 156° W.), is so pre-eminently rich in
Radiolaria that it often approaches in composition the Radiolarian ooze,
and has probably been derived from it. The track of the Challenger through
the tropical and northern parts of the Pacific describes nearly three sides
of a rectangle, which includes about half of the enormous Pacific basin,
and from this as well as from other supplementary observations it may with
great probability be concluded that by far the largest part of the bed of
the Pacific (at least three-fourths) is covered either with Radiolarian
ooze or with red clay, which contains a larger or smaller amount of the
remains of Radiolaria. With this agrees also the important fact that the
numerous preparations of pelagic materials and collections of pelagic
animals, which were collected by the Challenger in the Pacific, almost
always indicate a corresponding amount of Radiolarian life on the surface.
This is true in particular also of the South Pacific, between lat. 33° S.
and 40° S. (from long. 133° W. to 73° W., Stations 287 to 301); the surface
of this southern region and the different bathymetrical zones were rich in
new and peculiar species of Radiolaria.
A. Many specimens of bottom-deposits from the Pacific, which are entered
in the Challenger lists either as "red clay" or "Globigerina ooze,"
contain larger or smaller quantities of Radiolaria, and the number of
different species of SPUMELLARIA and NASSELLARIA which they contain is
often so great that the deposit might have been almost as appropriately
termed "Radiolarian ooze," _e.g._, Stations 241 to 245, and 270, 271
(compare §§ 236-239).
B. Pacific Radiolarian ooze was first obtained by Lieutenant Brooke (May
11, 1859) between the Philippines and Marianne Islands, from a depth of
3300 fathoms (lat. 18° 3' N., long. 129° 11' E.). Ehrenberg, who first
described it, found seventy-nine different species of Polycystina in it,
and reported "that their quantity and the number of different forms
increased with the depth" (Monatsber. d. k. preuss. Akad. d. Wiss.
Berlin, 1860, pp. 466, 588, 766).
230. _Fauna of the Indian Ocean._--As regards its Radiolarian fauna the
Indian Ocean is the least known of the three great basins. Still the few
limited spots, regarding which {cl}investigations are forthcoming, indicate
a very rich development of Radiolarian life. Probably it approaches more
nearly the fauna of the Pacific than that of the Atlantic, both as regards
the abundance and the morphological characters of its species. The
researches of the Challenger are very limited and incomplete as regards the
Indian Ocean, for the expedition only just touched upon this great ocean
basin (2000 to 3000 fathoms deep) at its two extremities (westwards at the
Cape of Good Hope and eastwards at Tasmania), its course lying for the most
part south of lat. 45° S. and extending beyond lat. 65° S. (from Station
149 to 158, south of lat. 50° S.). It is true that this portion of the
South Indian Ocean was shown to contain Radiolaria everywhere, but these
were more plentiful in individuals than in species. Only from Station 156
to Station 159 (between lat. 62° and 47° S., and long. 95° and 130° E.) was
the bottom, which consisted partly of Diatom ooze and partly of Globigerina
ooze, richer in species (see note A). The gaps left by the Challenger in
the investigation of the Indian Ocean, have, however, been to some extent
filled from other sources. As early as 1859 the English "Cyclops"
expedition had shown that the bottom of the Indian Ocean to the east of
Zanzibar (lat. 9° 37' S., long. 61° 33' W.) is covered with pure
Radiolarian ooze (see note B). Also since the Tertiary rocks of the Nicobar
Islands are for the most part of the same composition, and since a great
abundance of Radiolaria has been shown to be present both in the east part
of the ocean, between the Cocos Islands and the Sunda Archipelago (see note
C), and in the northern part or Arabian Sea between Socotra and Ceylon (see
note D); it may be assumed with great probability that the greater part of
the basin of the Indian Ocean, like that of the Pacific, is covered either
with Radiolarian ooze or with the characteristic red clay. With this agrees
the richness of the surface of the Indian Ocean in Radiolaria of the most
various groups, which has been more extensively demonstrated.
A. The Radiolarian fauna collected by the Challenger on the voyage from
the Cape to Melbourne, shows in part, namely, from Station 156 to Station
158, very peculiar and characteristic composition; in particular, the
Diatom ooze of Station 157 passes over in great part into a Radiolarian
ooze, mainly composed of #Sphærellaria#. This is worthy of a more
thorough investigation than I was able, owing to lack of material and
time, to give it.
B. The remarkably pure Radiolarian ooze of Zanzibar, discovered by
Ehrenberg in 1859, was the earliest known recent example of that deposit.
It was brought up by Captain Pullen of the English man-of-war "Cyclops,"
from a depth of 2200 fathoms, between Zanzibar and the Seychelles, and
"under a magnifying power of 300 diameters, showed at the first glance a
mass of almost pure Polycystina, such as no sample of a deep-sea deposit
has hitherto shown. It is very noticeable that in the whole of this mass
of living forms, no calcareous shells are to be seen" (Ehrenberg, L. N.
24, pp. 148, 149).
C. For the most important material from the Indian Ocean, I am indebted
to Captain Heinrich Rabbe of Bremen, who during many voyages in the
Indian Ocean, in his ship "Joseph Haydn," made numerous collections in
different localities with the tow-net and the trawl, and admirably
preserved the rich collections thus made. The greatest abundance of
Radiolaria was found in those {cli}obtained to the east of Madagascar,
and next in those from the neighbourhood of the Cocos Islands. I take
this opportunity of expressing my thanks to Captain Rabbe for the
liberality with which he placed all this valuable material at my
disposal.
D. On my voyage from Aden to Bombay, and thence to Ceylon (1881), and
especially on my return journey from Ceylon, between the Maldive Islands
and Socotra (1882), I carried on a number of experiments with a surface
net, which yielded a rich fauna of pelagic animals, and among them many
new species of Radiolaria, for observation. On several nights when the
smooth surface of the Indian Ocean, unrippled by any wind, shone with the
most lovely phosphorescent light, I drew up water from the surface with a
bucket, and obtained a rich booty. A number of other new species of
Radiolaria from very various parts of the Indian Ocean I obtained from
the alimentary canal of pelagic animals, such as Medusæ, Salpæ,
Crustacea, &c. Although the total number of Radiolaria known to me from
the Indian Ocean is much less than from the Atlantic and Pacific, there
are several new genera and numerous species among them, which show that a
careful study of this fauna will be of wide interest.
231. _Fauna of the Atlantic Ocean._--The Atlantic Ocean in all parts, of
which the pelagic fauna has been examined, has shown the same constant
presence of Radiolaria, and in certain parts of its abyssal deposits a
larger or smaller quantity of different types belonging to this class; on
the whole, however, its Radiolarian fauna is inferior to that of the
Pacific, and probably also to that of the Indian Ocean, both in quantity
and quality. Pure Radiolarian ooze, such as is so extensively found on the
floor of the Pacific, and in certain places in that of the Indian Ocean,
has not yet been found in the Atlantic (see § 237). The red clay, too, of
the deep Atlantic does not seem to be so rich in Radiolaria as that of the
Pacific; nevertheless, the number of species peculiar to the Atlantic is
very large, and at certain points the abundance of species as well as of
individuals seems to be scarcely less than in the Pacific. This is
especially true of the eastern equatorial zone not far from Sierra Leone,
Stations 347 to 352 (see note A); also of the South Atlantic between Buenos
Ayres and Tristan da Cunha, Stations 324, 325, 331 to 333 (see note B);
and, lastly, in the North Atlantic in the Gulf Stream and near the Canary
Islands (see note C). The fauna of the latter agrees for the most part with
that of the Mediterranean (see note D). In addition to the material
collected by the Challenger, other deep-sea investigations have furnished
bottom-deposits from different parts of the ocean, which have proved very
rich in Radiolaria (see note E). Furthermore, since the island of Barbados
consists for the most part of fossil Radiolarian ooze, it is very probable
that at certain parts of the tropical Atlantic true Radiolarian ooze, like
that of the Pacific and Indian Oceans, will eventually be found in depths
between 2000 and 3000 fathoms, perhaps over a considerable area.
A. The tropical zone of the eastern Atlantic seems to be especially rich
in peculiar Radiolaria of different species. This is shown by numerous
preparations from the surface, and from various depths (between lat. 3°
S. and 11° N., and long. 14° W. to 18° W.), which were made towards the
{clii}end of the cruise. Unfortunately no bottom-deposits were obtained
from the most important stations (except Nos. 346 and 347, depths 2350
and 2250 fathoms) in this region; at these the deposit was a Globigerina
ooze containing numerous different species of Radiolaria.
B. In the South Atlantic, between Buenos Ayres and Tristan da Cunha
(between lat. 35° S. and 43° S., long. 8° W. and 57° W.) there appears to
be a long stretch covered partly with Globigerina ooze (Stations 331 to
334), or red clay (Stations 329, 330), partly with blue mud (Stations 318
to 328), which contains not only large masses of individuals but numerous
peculiar species of SPUMELLARIA and NASSELLARIA. The preparations from
the surface-takings of this region are also rich in these, as well as in
peculiar PHÆODARIA.
C. The northern part of the Atlantic appears on the whole to be inferior
to the tropical and southern portions as regards its richness in
Radiolaria, and from the western half more especially, only few species
are known. From my researches at Lanzerote in 1866-67, it appears that
the pelagic fauna of the Canary Islands is very rich in them, as is also
the Gulf Stream in the neighbourhood of the Færöe Channel, according to
the investigations of John Murray (see his Report on the "Knight-Errant"
Expedition, Proc. Roy. Soc. Edin., vol. xi., 1882).
D. The Radiolaria of the Mediterranean are of special interest, because
almost all our knowledge of these organisms in the living conditions and
of their vital functions has been derived from investigations conducted
on its shores. Johannes Müller laid the foundation of this knowledge by
his investigations at Messina, and on the Ligurian and French coasts at
Nice, Cette, and St. Tropez (L. N. 10). The many new Radiolaria which I
described in my Monograph (L. N. 16, 1862), were for the most part taken
at Messina, the place which possesses a richer pelagic fauna than any
other, so far as is yet known, in the Mediterranean. Other new species I
found afterwards at Villafranca near Nice, in 1864 (L. N. 19), at
Portofino near Genoa (1880), at Corfu (1877), and at other points on the
coast. In Messina also, Richard Hertwig collected the material for his
valuable treatise on the Organisation of the Radiolaria (L. N. 33), after
he had previously made investigations into their histology at Ajaccio in
Corsica (L. N. 26). Lastly, at Naples, Cienkowski (L. N. 22) and Karl
Brandt (L. N. 38, 39, 52) carried out their important investigations into
the reproduction and symbiosis of the Radiolaria. With respect to the
character of its Radiolaria, the Mediterranean fauna is to be regarded as
a special province of the North Atlantic.
E. Among the smaller contributions which have been made towards our
knowledge of the Atlantic Radiolarian fauna, the communications of
Ehrenberg on the deposits obtained in sounding for the Atlantic cable,
and on the Mexican Gulf Stream near Florida, deserve special mention (L.
N. 24, pp. 138, 139-145).
232. _Vertical Distribution._--The most important general result of the
discoveries of the Challenger, as regards the vertical or bathymetrical
distribution of the Radiolaria, is the interesting fact that numerous
species of this class are found living at the most various depths of the
sea, and that certain species are limited to particular bathymetrical
zones, _i.e._, are adapted to the conditions which obtain there. In this
respect three different Radiolarian faunas may be distinguished, which may
be shortly termed "pelagic," "zonarial," and "abyssal." The _pelagic_
Radiolaria swim at the surface, and when they sink (_e.g._, in a stormy
sea), only descend to a small depth, probably not more than from {cliii}20
to 30 fathoms (§ 233). The complicated conditions of existence created by
the keen struggle for existence at the surface of the sea, give rise to the
formation of very numerous pelagic species, especially of Porulosa
(SPUMELLARIA and ACANTHARIA). The _abyssal_ Radiolaria are very different
from those just mentioned; they live at the bottom of the deep-sea, not
resting upon nor attached to it, but probably floating at a little distance
above it, and are adapted to the conditions of existence which obtain there
(§ 235). Here the Osculosa (NASSELLARIA and PHÆODARIA) seem to predominate.
The _zonarial_ Radiolaria live floating at various depths between the
pelagic and abyssal species (§ 234). In their morphological characters they
gradually approach the pelagic forms upwards and the abyssal downwards.
The views which have hitherto been held regarding the bathymetrical or
vertical distribution of the Radiolaria have been entirely altered by the
magnificent discoveries of the Challenger, and especially by the
important observations of Sir Wyville Thomson (L. N. 31) and John Murray
(L. N. 27). These two distinguished deep-sea explorers have, as a result
of their wide experience, been convinced that Radiolaria exist at all
depths of the ocean, and that there are large numbers of true deep-sea
species which are never found at the surface of the sea nor at slight
depths (L. N. 31, vol. i. pp. 236-238; L. N. 27, pp. 523, 525). The
result of my ten years' work upon the Challenger Radiolaria, and the
comparative study of more than a thousand mountings from all depths, has
only been to confirm this opinion, and I am further persuaded that it
will some day be possible by the aid of suitable nets (not yet invented)
to distinguish different faunistic zones in the various depths of the
sea. In this connection may be mentioned the specially interesting fact
that the species of Radiolaria of one and the same family present in the
different depths characteristic morphological distinctions, which
obviously correspond to their different physiological relations in the
struggle for existence. Owing to those extensive discoveries, the
representation which I gave in my Monograph (1862, L. N. 16, pp. 172-196)
of the vertical distribution of the Radiolaria, and of their life in the
greatest depths of the sea, has been entirely changed. Compare also
Bütschli (L. N. 41, p. 466).
233. _The Pelagic Fauna._--The surface of the open ocean seems everywhere,
at a certain distance from the coast at least, to be peopled by crowds of
living Radiolaria. In the tropical zone these pelagic crowds consist of
many different species, whilst in the frigid zones, on the other hand, they
are made up of many individuals belonging to but few species. Most of these
inhabitants of the surface may be regarded as truly pelagic species, which
either remain always at the surface or descend only very slightly below it.
Probably most Porulosa (both SPUMELLARIA and ACANTHARIA) belong to this
group; whilst but few Osculosa occur in it, and fewer PHÆODARIA than
NASSELLARIA. In general the pelagic Radiolaria are distinguished from the
abyssal by the more delicate and slender structure of their skeletons; the
pores of the lattice-shells are larger, the intervening trabeculæ thinner;
the armature of spines, spathillæ, anchors, &c., is more various and more
highly developed. Numerous forms are to be found among the pelagic
{cliv}Radiolaria which have either an incomplete skeleton or none at all.
When the pelagic forms leave the surface on account of unfavourable
weather, they appear only to sink to slight depths (probably not below 20
or 30 fathoms). Within the limits of the same family the size of the
pelagic species seems to be on an average greater than that of the related
abyssal forms.
234. _The Zonarial Fauna._--Between the pelagic fauna living at the surface
of the open sea and the abyssal, which floats immediately over the bottom,
there appears to be usually a middle fauna, which inhabits the different
bathymetrical zones of the intermediate water, and hence may be shortly
called the "zonarial" fauna. The different species of Radiolaria which
inhabit these different strata in the same vertical column of water present
differences corresponding to those of the plants composing the several
zones of vegetation, which succeed each other at different heights on a
mountain; they correspond to the different conditions of existence which
are presented by the different strata of water, and to which they have
become adapted in the struggle for existence. The existence of such
bathymetrical zones has been shown by those important, if not numerous,
observations of the Challenger, in which the tow-net was used at different
depths at one and the same Station. In several cases the character of the
Radiolarian fauna at different depths presented characteristic differences.
For the present, and until we are better acquainted with the characters
of the Radiolarian fauna at different depths, we may distinguish
provisionally the following _five bathymetrical zones_:--(1) The
_pelagic_ zone, extending from the surface to a depth of about 25
fathoms; (2) the _pellucid_ zone, extending from 25 to 150 fathoms, or as
far as the influence of the sunlight makes itself felt; (3) the _obscure_
zone, extending from 150 to 2000 fathoms, or from the depth at which
sunlight disappears to that at which the influence of the water
containing carbonic acid begins and the calcareous organisms vanish; (4)
the _siliceous_ zone, extending from 2000 or 2500 to about 3000 fathoms,
in which only siliceous not calcareous Rhizopoda are found, and in which
the peculiar conditions of the lowest regions have not yet appeared; (5)
the _abyssal_ zone, in which the accumulation of the oceanic deposits,
and the influence of the bottom currents, create new conditions of
existence. So far as our isolated and incomplete observations of the
zonarial Radiolarian fauna extend, it appears that the subclass Porulosa
(SPUMELLARIA and ACANTHARIA) predominates in the two upper zones, and as
the depth increases is gradually replaced by the subclass Osculosa
(NASSELLARIA and PHÆODARIA), so that the latter predominates in the two
lowest zones. The obscure zone which lies in the middle is probably the
poorest in species. In general, the morphological characters of the
zonarial fauna appear to change gradually upwards into the delicate form
of the pelagic and downwards into the robust constitution of the abyssal;
so also the average size of the individuals (within the limits of the
same family) appears to increase upwards and decrease downwards.
235. _The Abyssal Fauna._--The great majority of Radiolaria which have
hitherto been observed, and which are described in the systematic portion
of this Report, have been obtained from the bottom of the deep-sea, and
more than half of all the species have been {clv}derived from the pure
Radiolarian ooze, which forms the bed of the Central Pacific at depths of
from 2000 to 4000 fathoms (§ 237). Many of these abyssal forms were brought
up with the malacoma uninjured, and they show, both when mounted
immediately in balsam, and when preserved in alcohol, all the soft parts
almost as clearly as fresh preparations of pelagic Radiolaria. These
species are to be regarded as truly abyssal, _i.e._, as forms which live
floating only a little distance above the bottom of the deep-sea, having
become adapted to the peculiar conditions of life which obtain in the
lowest regions of the ocean. Probably the majority of the PHÆODARIA belong
to these abyssal Radiolaria, as well as a large number of NASSELLARIA, but
on the other hand, only a small number of ACANTHARIA and SPUMELLARIA are
found there. A character common to these abyssal forms, and rarely found in
those from the surface or from slight depths, is found in their small size
and their heavy massive skeletons, in which they strikingly resemble the
fossil Radiolaria of Barbados and the Nicobar Islands. The lattice-work of
the shell is coarser, its trabeculæ thicker and its pores smaller than in
pelagic species of the same group; also the apophyses (spines, spathillæ,
coronets, &c.), are much less developed than in the latter. From these true
abyssal Radiolaria must be carefully distinguished those species whose
empty skeletons, devoid of all soft parts, occur also in the Radiolarian
ooze of the deep-sea, but are clearly only the sunken remains of dead
forms, which have lived at the surface or in some of the upper zones.
236. _Deposits containing Radiolaria._--The richest collection of
Radiolaria is found in the deposits of ooze which form the bed of the
ocean. Although the pelagic material skimmed from the surface of the sea,
and the zonarial material taken by sinking the tow-net to various depths,
are always more or less rich in Radiolaria, still the number of species
thus obtained is, on the whole, much less than has hitherto been got merely
from deep-sea deposits. Of course the skeletons found in the mud of the
ocean-bed, may belong either to the abyssal species which live there (§
235), or to the zonarial (§ 234), or to the pelagic species (§ 233), for
the siliceous skeletons of these latter sink to the bottom after their
death. Almost all these remains found in the deposits belong to the
siliceous "Polycystina" (SPUMELLARIA and NASSELLARIA); PHÆODARIA occur but
sparingly, and ACANTHARIA are entirely wanting, for their acanthin skeleton
readily dissolves. The abundance of Radiolaria varies greatly according to
the composition and origin of the deposits. In general marine deposits may
be divided into two main divisions, terrigenous and abyssal, or, more
shortly, muds and oozes. The _terrigenous_ deposits (or muds) include all
those sediments which are made up for the most part of materials worn away
from the coasts of continents and islands, or brought down into the sea by
rivers. Their greatest extent from the coast is about 200 nautical miles.
They contain varying quantities of Radiolaria, but much fewer than those of
the next group. The _abyssal_ deposits (or oozes) usually commence at a
distance of from 100 to 200 nautical miles {clvi}from the coast. In general
they are characterised by great uniformity, corresponding to the constancy
of the conditions under which they are laid down; they may be divided into
three categories, the true Radiolarian ooze (§ 237), Globigerina ooze (§
238), and red clay (§ 239). Of these three most important deep-sea
formations the first is by far the richest in Radiolaria, although the
other two contain often very many siliceous shells.
The marvellous discoveries of the Challenger have thrown upon the nature
of marine deposits an entirely new light, which justifies most important
conclusions regarding the geographical distribution and geological
significance of the Radiolaria. Since Dr. John Murray and the Abbé Renard
will treat fully of these interesting relations in a forthcoming volume
of the Challenger series (Report on the Deep-Sea Deposits), it will be
sufficient here to refer to their preliminary publication already
published (Narrative of the Cruise of H.M.S. Challenger, 1885, vol. ii.
part ii. pp. 915-926); see also the earlier communications by John Murray
(1876, L. N. 27, pp. 518-537), and by Sir Wyville Thomson (The Atlantic,
L. N. 31, vol. i. pp. 206-246). In the Narrative (_loc. cit._, p. 916)
the following table of marine deposits is given:--
{Shore formations, } Found in inland
{Blue mud, } seas and along the
{Green mud and sand, } shores of
{Red mud, } continents.
Terrigenous deposits.{
{Volcanic mud and sand, } Found around oceanic
{Coral mud and sand, } islands and along the
{Coralline mud and sand, } shores of continents.
{Globigerina ooze, } Found in the abysmal
{Pteropod ooze, } regions of the
Abysmal deposits. {Diatom ooze, } ocean basins.
{Radiolarian ooze, }
{Red clay, }
237. _Radiolarian Ooze._--By Radiolarian ooze, in the strict sense of the
term, are understood those oceanic deposits, the greater part of which
(often more than three-quarters) is composed of the siliceous skeletons of
this class. Such _pure_ Radiolarian ooze has only been found in limited
areas of the Pacific and Indian Oceans. It is most conspicuous in the
Central Pacific, between lat. 12° N. and 8° S., long. 148° W. to 152° W.,
the depth being everywhere between 2000 and 3000 fathoms (Stations 266 to
268 and 272 to 274). In the deepest of the Challenger soundings (Station
225, 4475 fathoms) the bottom is composed of pure Radiolarian ooze, as well
as at the next Station in the Western Tropical Pacific (Station 226, 2300
fathoms), the latitude varying from 12° N. to 15° N., and the longitude
from 142° E. to 144° E. In the Indian Ocean also, pure Radiolarian ooze was
found in the year 1859 between Zanzibar and the Seychelles, this being the
first known example of it (§ 230). On the other hand, it has not yet been
found in the bed of the Atlantic; but the Tertiary formations of Barbados
(Antilles, § 231) like those of the Nicobar Islands (Further India), are to
be regarded as pure Radiolarian {clvii}ooze in the fossil condition.
_Mixed_ Radiolarian ooze is the name given to those deposits in which the
Radiolaria exceed any of the other organic constituents, although they do
not make up half the total mass. To this category belong a large number of
the Challenger soundings which are entered in the Station list either as
red clay or Globigerina ooze. Such mixed Radiolarian ooze has been
discovered (A) in the North Pacific in an elongated area of red clay
extending from Station 241 to Station 245 (perhaps even from Station 238 to
Station 253), that is, at least, from long. 157° E. to 175° E., between
lat. 35° N. and 37° N.; (B) in the tropical Central Pacific in the
Globigerina ooze of Stations 270 and 271. The ooze from the latter station,
situated almost on the equator (lat. 0° 33' S., long. 151° 34' W.), is
specially remarkable, for it has yielded more new species of SPUMELLARIA
and NASSELLARIA than any other Station, not excluding even the neighbouring
Stations 268, 269, and 272. Probably such mixed Radiolarian ooze is very
widely distributed in the depths of the ocean, as, for example, in the
South Pacific (Stations 288, 289, 300, and 302), and in the Southern Ocean
(Stations 156 to 159); also in the South Atlantic (Stations 324, 325, 331,
332) and in the tropical Atlantic (Stations 348 to 352). When carefully
purified and decalcified by acids, Radiolarian ooze appears as a fine
shining white powder; in the raw state it is yellowish or reddish,
sometimes reddish-brown or dark brown in colour, according to the quantity
of oxides of iron, manganese, &c., which it contains. Calcareous skeletons
(especially the tests of pelagic Foraminifera) do not occur at all or only
in very minute quantities in _pure_ Radiolarian ooze from more than 2000
fathoms, whilst specimens of _mixed_ ooze often contain considerable
quantities of them.
Pure Radiolarian ooze was first described by Dr. John Murray as regards
its peculiar nature and composition under the name "Radiolarian ooze"
(1876, L. N. 27, pp. 525, 526); compare also Sir Wyville Thomson (The
Atlantic, L. N. 31, vol. i. pp. 231-238), and John Murray (Narr. Chall.
Exp., L. N. 53, vol. i. pt. ii. pp. 920-926, pl. N. fig. 2). The
different specimens of pure Radiolarian ooze obtained by the Challenger
from the Pacific, and handed to me for investigation, are from depths of
from 2250 fathoms to 4475 fathoms, and may be divided according to their
composition into three different groups:--I. The Radiolarian ooze of the
Western Tropical Pacific, Stations 225 and 226, from depths of 4475 and
2300 fathoms (lat. 11° N. to 15° N., and long. 142° E. to 144° E.). II.
The Radiolarian ooze of the northern half of the Central Pacific,
Stations 265 to 269, from depths of 2550 to 2900 fathoms. III. The
Radiolarian ooze of the southern half of the Central Pacific, Stations
270 to 274, from depths of 2350 to 2925 fathoms. A fourth group would be
constituted by the Radiolarian ooze from the Philippines, which was
brought up by Brooke in 1860 near the Marianne Islands from 3300 fathoms,
and described by Ehrenberg (Monatsber. d. k. preuss. Akad. d. Wiss.
Berlin, 1860, p. 765). The Diatom ooze, too, found by the Challenger in
the Antarctic regions (Stations 152 to 157) is in some parts so rich in
Radiolaria that it passes over into true Radiolarian ooze. Regarding the
Radiolarian ooze from Zanzibar, obtained by Captain Pullen in 1859 from
2200 fathoms (§ 230), we have only the incomplete communications of
Ehrenberg (L. N. 24, p. 147). A more accurate knowledge of these deposits
from the Indian Ocean, and of {clviii}those which we may with probability
expect from the tropical eastern Atlantic, will be sure to increase very
widely our knowledge of the class.
238. _Globigerina Ooze._--Next to the Radiolarian ooze proper the
Globigerina ooze is the deposit which is richest in the remains of
Radiolaria. Often these are so abundant that it is doubtful to which
category the specimen should be referred (_e.g._, Stations 270 and 271, see
§ 237). In fact, the two pass without any sharp boundary into each other,
and both present transitions to the Diatom ooze. Next to red clay (§ 239),
Globigerina ooze is the most widely distributed of all sediments, and forms
a large part of the bed of the ocean at depths of 250 to 2900 fathoms
(especially between 1000 and 2000 fathoms). It covers extensive areas at
depths below 1800 fathoms, and in still deeper water is replaced by red
clay. It is a fine-grained white, grey, or yellowish powder, which
sometimes becomes coloured rose, red, or brown owing to the admixture of
oxides of iron and manganese. True Globigerina ooze consists for the most
part of the accumulated calcareous shells of pelagic Foraminifera,
principally _Globigerina_ and _Orbulina_, but also _Hastigerina_,
_Pulvinulina_, &c. It contains usually from 50 to 80 per cent. of calcium
carbonate, the extreme values being 40 and 95 per cent. After this has been
removed by acids, there remains a residue, which consists partly of the
siliceous shells of Radiolaria and Diatoms, and partly of mineral particles
identical with the volcanic elements of the red clay.
Regarding the composition and significance of the Globigerina ooze, see
John Murray (L. N. 27, pp. 523-525, and L. N. 53, vol. i. p. 919).
Recently this author has separated from the Globigerina ooze (_sensu
stricto_), the _Pteropod ooze_, distinguished from the former by the
greater abundance of Pteropod shells and calcareous shells of larger
pelagic organisms which it contains. It is found in moderate depths (at
most 1500 fathoms), and contains fewer Radiolaria.
239. _Red Clay._--This is quantitatively the most important of all deep-sea
deposits, covering by far the greatest extent of the three great ocean
basins at depths greater than 2200 fathoms. It thus far surpasses in area
the other deposits, both Radiolaria and Globigerina oozes, and commonly
forms a still deeper layer beneath them. Probably these three deep-sea
deposits together cover about three-eighths of the whole surface of the
earth, that is, about as much as all the continents together, whilst only
two-eighths are covered by the terrigenous deposits. Red clay is
principally composed of silicate of alumina, mixed in various proportions
with other finely granular substances; its usual red colour, which
sometimes passes over into grey or brown, is more especially due to
admixture of oxides of iron and manganese. Calcareous matter is usually
entirely wanting, or present only in traces, whilst free silica is found in
very variable, often considerable quantities. The chief mass of the red
clay consists of volcanic ashes, pumice, fragments of lava, &c., whilst a
large part of it is generally composed of shells of Radiolaria or fragments
of {clix}them; in many places the number of well-preserved skeletons
contained in the red clay is very considerable, so that it passes over
gradually into the Radiolarian ooze (_e.g._, in the North Pacific, Stations
238 to 253, see § 237). Hence it may be supposed that a large part of the
red clay consists of decomposed Radiolarian ooze.
The characteristic composition and fundamental significance of the red
clay in the formation of the deep-sea bed were first made known by the
discoveries of the Challenger (compare John Murray, 1876, L. N. 27, p.
527, and Narr. Chall. Exp., L. N. 53, vol. i. pt. ii. pp. 920-926, pl. N;
also Wyville Thomson, The Atlantic, L. N. 31, vol. i. pp. 226-229). The
mineral components of the red clay are for the most part of volcanic
origin, due to the decomposition of pumice, lava, &c. Among the organic
remains found in it, the siliceous skeletons of Radiolaria are by far the
most important, and their number is often considerable. A large portion
of the red clay appears to me to consist of broken down Radiolarian
shells, in which a peculiar metamorphism probably has taken place. Sir
Wyville Thomson was of opinion that a considerable proportion of it
consisted of the remains of Globigerina ooze, the calcareous constituents
of which had been removed by the carbon dioxide in the deep-sea water (L.
N. 31, _loc. cit._). Among these remains, however, the siliceous
skeletons of the Radiolaria play a significant and often the most
important part. Furthermore, John Murray has called attention to the fact
that in many deep-sea deposits yellow and red insoluble particles remain,
which unmistakably present the form of Radiolarian shells (L. N. 27, p.
513). At Station 303 he found "amorphous clayey matter, rounded yellow
minerals, many Radiolaria-shaped;" at Station 302 there was sediment
"consisting almost entirely of small rounded red mineral particles; many
of these had the form of both Foraminifera and Radiolaria; and it seemed
as if some substance had been deposited in and on these organisms."
Similar transitions from well-preserved Radiolarian shells into amorphous
mineral particles I have found in several other specimens of Challenger
soundings, and consider them a further argument for the supposition that
the Radiolaria often take an important share in the formation of the red
clay.
240. _List of Stations at which Radiolaria were observed on the Challenger
Expedition._--The 168 Stations recorded below, in soundings or surface
preparations from which I found Radiolaria, belong to the most various
parts of the sea which the Challenger traversed during her voyage round the
world; they constitute about half of the (364) observing Stations contained
in the official list published in the Narrative of the Cruise (Narr. Chall.
Exp., vol. i. part ii. Appendix ii.).
In addition to the particulars given in the list regarding the
geographical position of the Station, depth, temperature, and composition
of the bottom deposit, I have added the result of my investigations as
regards the relative abundance of the Radiolaria in each. The five
letters (A to E) denote the following degrees of frequency:--A, abundant
Radiolaria (AI, pure Radiolarian ooze; AII, mixed Radiolarian ooze); B,
very numerous Radiolaria (but not a predominating quantity); C, many
Radiolaria (medium quantity); D, few Radiolaria; E, very few Radiolaria
(as they occur almost always). In using these symbols regard has been had
to abundance of the abyssal as well as of the zonarial and pelagic forms
(§ 232); sometimes also the estimated number of Radiolaria has been
inserted, based upon information given by John Murray in his Preliminary
Report (L. N. 27), and in the Narrative of the Cruise (L. N. 53), as well
as by Henry B. Brady in his Report on the {clx}Foraminifera (Zool. Chall.
Exp., part xxii., 1884). From Stations 348 to 352 in the Eastern Tropical
Atlantic no specimens of the bottom were obtained, but a rich pelagic
Radiolarian fauna was demonstrated by numerous preparations from the
surface. The depths are given in fathoms and the temperature in degrees
Fahrenheit. In the column describing the nature of the bottom the
following abbreviations are used:--
rad. oz. = Radiolarian ooze (§ 237).
gl. oz. = Globigerina ooze (§ 238).
r. cl. = red clay (§ 239).
pt. oz. = Pteropod ooze (see p. clviii).
di. oz. = Diatom ooze (see p. clvii).
bl. m. = blue mud, } terrigenous deposits
gr. m. = green mud, } (see p. clvi).
volc. m. = volcanic mud, }
r. m. = red mud.
+----------+-----------+--------+------------+-----------+--------------+
| | | | Bottom | | Relative |
|Challenger| Locality. |Depth in|Temperature,| Nature of | Abundance of |
| Station. | |Fathoms.| ° F. | Bottom. | Radiolaria. |
+----------+-----------+--------+------------+-----------+--------------+
| | | | | | |
| 1. | N. Atl. | 1890 | 36.8 | gl. oz. | D few |
| 2. | " | 1945 | 36.8 | gl. oz. | E very few |
| 5. | " | 2740 | 37.0 | r. cl. | D few |
| 9. | " | 3150 | 36.8 | r. cl. | E very few |
| 24. | Tr. Atl. | 390 | ... | pt. oz. | D few |
| | | | | | |
| 32. | N. Atl. | 2250 | 36.7 | gl. oz. | E very few |
| 45. | " | 1240 | 37.2 | bl. m. | E " |
| 50. | " | 1250 | 38.0 | bl. m. | E " |
| 64. | " | 2700 | ... | r. cl. | D few |
| 76. | " | 900 | 40.0 | pt. oz. | D " |
| | | | | | |
| 98. | Tr. Atl. | 1750 | 36.7 | gl. oz. | C many |
| 106. | " | 1850 | 36.6 | gl. oz. | C " |
| 108. | " | 1900 | 36.8 | gl. oz. | C " |
| 111. | " | 2475 | 33.7 | gl. oz. | C " |
| 120. | " | 675 | ... | r. m. | D few |
| | | | | | |
| 132. | S. Atl. | 2050 | 35.0 | gl. oz. | C many |
| 134. | " | 2025 | 36.0 | gl. oz. | C " |
| 137. | " | 2550 | 34.5 | r. cl. | D few |
| 138. | " | 2650 | 35.1 | r. cl. | D " |
| 143. | S. Ind. | 1900 | 35.6 | gl. oz. | E very few |
| | | | | | |
| 144. | " | 1570 | 35.8 | gl. oz. | E " |
| 145. | " | 140 | ... | volc. s. | D few |
| 146. | " | 1375 | 35.6 | gl. oz. | C many |
| 147. | " | 1600 | 34.2 | di. oz. | C " |
| 148. | " | 210 | ... {| gravel, } | D few |
| | | | {| shells } | |
| | | | | | |
| 149H. | " | 127 | ... | volc. m. | D " |
| 150. | " | 150 | 35.2 | gravel | D " |
| 151. | " | 75 | ... | volc. m. | D " |
| 152. | " | 1260 | ... | di. oz. | C many |
| 153. | " | 1675 | ... | bl. m. | C " |
| | | | | | |
| 154. | " | 1800 | ... | bl. m. | C " |
| 155. | " | 1300 | ... | bl. m. | C " |
| 156. | " | 1975 | ... | di. oz. | B numerous |
| 157. | " | 1950 | 32.1 | di. oz. | B " |
| 158. | " | 1800 | 33.5 | gl. oz. | B " |
| | | | | | |
| 159. | " | 2150 | 34.5 | gl. oz. | B " |
| 160. | " | 2600 | 33.9 | r. cl. | C many |
| 162. | " | 38 | ... | sand | E very few |
| 163. | S. Pac. | 2200 | 34.5 | gr. m. | E " |
| 164A. | " | 1200 | ... | gr. m. | E " |
| | | | | | |
| 165. | S. Pac. | 2600 | 34.5 | r. cl. | D few |
| 166. | " | 275 | 50.8 | gl. oz. | D " |
| 169. | " | 700 | 40.0 | bl. m. | D " |
| 175. | Tr. Pac. | 1350 | 36.0 | gl. oz. | E very few |
| 181. | " | 2440 | 35.8 | r. cl. | E " |
| | | | | | |
| 193. | " | 2800 | 38.0 | bl. m. | D few |
| 195. | " | 1425 | 38.0 | bl. m. | C many |
| 197. | " | 1200 | 35.9 | bl. m. | D few |
| 198. | " | 2150 | 38.9 | bl. m. | C many |
| 200. | " | 250 | ... | gr. m. | B numerous |
| | | | | | |
| 201. | " | 82 | ... | st. & gra.| C many |
| 202. | " | 2550 | 50.5 | bl. m. | B numerous |
| 205. | " | 1050 | 37.0 | bl. m. | C many |
| 206. | " | 2100 | 36.5 | bl. m. | B numerous |
| 211. | " | 2225 | 50.5 | bl. m. | B " |
| | | | | | |
| 213. | " | 2050 | 38.8 | bl. m. | C many |
| 214. | " | 500 | 41.8 | bl. m. | C " |
| 215. | " | 2550 | 35.4 | r. cl. | C many |
| 216A | " | 2000 | 35.4 | gl. oz. | B numerous |
| 217. | " | 2000 | 35.2 | bl. m. | C many |
| | | | | | |
| 218. | " | 1070 | 36.4 | bl. m. | C " |
| 220. | " | 1100 | 36.2 | gl. oz. | C " |
| 221. | " | 2650 | 35.4 | r. cl. | B numerous |
| 222. | " | 2450 | 35.2 | r. cl. | B " |
| 223. | " | 2325 | 35.5 | gl. oz. | B " |
| | | | | | |
| 224. | " | 1850 | 35.4 | gl. oz. | B " |
| 225. | " | 4475 | 35.2 | rad. oz. | A very many |
| 226. | " | 2300 | 35.5 | rad. oz. | A " |
| 230. | N. Pac. | 2425 | 35.5 | r. cl. | C many |
| 231. | " | 2250 | 35.2 | bl. m. | C " |
| | | | | | |
| 232. | " | 345 | 41.1 | gr. m. | C " |
| 234. | " | 2675 | 35.8 | bl. m. | B numerous |
| 235. | " | 565 | 38.1 | gr. m. | D few |
| 236. | " | 775 | 37.6 | gr. m. | C many |
| 237. | " | 1875 | 35.3 | bl. m. | C " |
| | | | | | |
| 238. | " | 3950 | 35.0 | r. cl. | B numerous |
| 239. | " | 3625 | 35.1 | r. cl. | B " |
| 240. | " | 2900 | 34.9 | r. cl. | B " |
| 241. | " | 2300 | 35.1 | r. cl. | A very many |
| 242. | " | 2575 | 35.1 | r. cl. | AII " |
| | | | | | |
| 243. | " | 2800 | 35.0 | r. cl. | AII " |
| 244. | " | 2900 | 35.3 | r. cl. | AII " |
| 245. | " | 2775 | 34.9 | r. cl. | AII " |
| 246. | " | 2050 | 35.1 | gl. oz. | B numerous |
| 247. | " | 2530 | 35.2 | r. cl. | C many |
| | | | | | |
| 248. | " | 2900 | 35.1 | r. cl. | C " |
| 249. | " | 3000 | 35.2 | r. cl. | B numerous |
| 250. | " | 3050 | 35.0 | r. cl. | B " |
| 251. | " | 2950 | 35.1 | r. cl. | B " |
| 252. | " | 2740 | 35.3 | r. cl. | B " |
| | | | | | |
| 253. | " | 3125 | 35.1 | r. cl. | B " |
| 254. | " | 3025 | 35.0 | r. cl. | C many |
| 255. | " | 2850 | 35.0 | r. cl. | C " |
| 256. | " | 2950 | 35.2 | r. cl. | B numerous |
| 257. | " | 2875 | 34.9 | r. cl. | C many |
| | | | | | |
| 258. | " | 2775 | 35.2 | r. cl. | C " |
| 259. | Tr. Pac. | 2225 | 34.9 | r. cl. | C " |
| 261. | " | 2050 | 35.2 | volc. m. | C many |
| 262. | " | 2875 | 35.2 | r. cl. | C " |
| 263. | " | 2650 | 35.1 | r. cl. | B numerous |
| | | | | | |
| 264. | " | 3000 | 35.2 | r. cl. | C many |
| 265. | " | 2900 | 35.0 | r. cl. | A very many |
| 266. | " | 2750 | 35.1 | rad. oz. | A " |
| 267. | " | 2700 | 35.0 | rad. oz. | A " |
| 268. | " | 2900 | 34.8 | rad. oz. | A " |
| | | | | | |
| 269. | " | 2550 | 35.2 | rad. oz. | A " |
| 270. | " | 2925 | 34.6 | gl. oz. | A " |
| 271. | " | 2425 | 35.0 | gl. oz. | A " |
| 272. | " | 2600 | 35.1 | rad. oz. | A " |
| 273. | " | 2350 | 34.5 | rad. oz. | A " |
| | | | | | |
| 274. | " | 2750 | 35.1 | rad. oz. | A " |
| 275. | " | 2610 | 35.0 | r. cl. | B numerous |
| 276. | " | 2350 | 35.1 | r. cl. | C many |
| 280. | " | 1940 | 35.3 | gl. oz. | D few |
| 281. | " | 2385 | 34.9 | r. cl. | C many |
| | | | | | |
| 282. | S. Pac. | 2450 | 35.1 | r. cl. | C " |
| 283. | " | 2075 | 35.4 | gl. oz. | D few |
| 284. | " | 1985 | 35.1 | gl. oz. | C many |
| 285. | " | 2375 | 35.0 | r. cl. | D few |
| 286. | " | 2335 | 34.8 | r. cl. | D " |
| | | | | | |
| 287. | " | 2400 | 34.7 | r. cl. | D " |
| 288. | " | 2600 | 34.8 | r. cl. | B numerous |
| 289. | " | 2550 | 34.8 | r. cl. | B " |
| 290. | " | 2300 | 34.9 | r. cl. | C many |
| 291. | " | 2250 | 34.6 | r. cl. | C " |
| | | | | | |
| 292. | " | 1600 | 35.2 | gl. oz. | C " |
| 293. | " | 2025 | 34.4 | gl. oz. | C " |
| 294. | " | 2270 | 34.6 | r. cl. | D few |
| 295. | " | 1500 | 35.3 | gl. oz. | C many |
| 296. | " | 1825 | 35.3 | gl. oz. | D few |
| | | | | | |
| 297. | " | 1775 | 35.5 | gl. oz. | D " |
| 298. | " | 2225 | 35.6 | bl. m. | C many |
| 299. | " | 2160 | 35.2 | bl. m. | C " |
| 300. | " | 1375 | 35.5 | gl. oz. | B numerous |
| 302. | " | 1450 | 35.6 | gl. oz. | B " |
| | | | | | |
| 303. | " | 1325 | 36.0 | bl. m. | D few |
| 304. | " | 45 | ... | gr. m. | E very few |
| 318. | S. Atl. | 2040 | 33.7 | bl. m. | C few |
| 319. | " | 2425 | 32.7 | bl. m. | C " |
| 323. | " | 1900 | 33.1 | bl. m. | C " |
| | | | | | |
| 324. | " | 2800 | 32.6 | bl. m. | B numerous |
| 325. | " | 2650 | 32.7 | bl. m. | B " |
| 326. | " | 2775 | 32.7 | bl. m. | C many |
| 327. | " | 2900 | 32.8 | bl. m. | C " |
| 328. | " | 2900 | 32.9 | bl. m. | B numerous |
| | | | | | |
| 329. | " | 2675 | 32.3 | r. cl. | C many |
| 330. | " | 2440 | 32.7 | r. cl. | C " |
| 331. | " | 1715 | 35.4 | gl. oz. | B numerous |
| 332. | " | 2200 | 34.0 | gl. oz. | B " |
| 333. | " | 2025 | 35.3 | gl. oz. | B " |
| | | | | | |
| 334. | " | 1915 | 35.8 | gl. oz. | C many |
| 335. | " | 1425 | 37.0 | pt. oz. | D few |
| 338. | Tr. Atl. | 1990 | 36.3 | gl. oz. | D few |
| 340. | " | 1500 | 37.6 | pt. oz. | E very few |
| 341. | " | 1475 | 38.2 | pt. oz. | E " |
| | | | | | |
| 342. | " | 1445 | 37.5 | pt. oz. | D few |
| 343. | " | 425 | 40.3 | volc. s. | E very few |
| 344. | " | 420 | ... | volc. s. | E " |
| 345. | " | 2010 | 36.8 | gl. oz. | D few |
| 346. | " | 2350 | 34.0 | gl. oz. | C many |
| | | | | | |
| 347. | " | 2250 | 36.2 | gl. oz. | B numerous |
| 348. | " | (2450) | ... | (Pelag.) | B " |
| 349. | " | ... | ... | (Pelag.) | B " |
| 350. | " | ... | ... | (Pelag.) | B " |
| 351. | " | ... | ... | (Pelag.) | B " |
| | | | | | |
| 352. | " | ... | ... | (Pelag.) | B " |
| 353. | N. Atl. | 2965 | 37.6 | r. cl. | C many |
| 354. | " | 1675 | 37.8 | gl. oz. | D few |
+----------+-----------+--------+------------+-----------+--------------+
+----------+--------+-----------------------+---------------------------+
| | | | |
|Challenger| Date. |Latitude and Longitude.| Nearest Land. |
| Station. | | | |
+----------+--------+-----------------------+---------------------------+
| | 1873. | | |
| 1. |Feb. 15|27° 24' N., 16° 55' W.|S. of Tenerife. |
| 2. | " 17|25° 52' N., 19° 22' W.|S.W. of the Canary Islands.|
| 5. | " 21|24° 20' N., 24° 28' W.|S.W. of the Canary Islands.|
| 9. | " 26|23° 23' N., 35° 11' W.| (Ocean). |
| 24. |Mar. 25|18° 38' N., 65° 5' W.|Culebra (Antilles). |
| | | | |
| 32. |April 3|31° 49' N., 64° 55' W.|Bermuda. |
| 45. |May 3|38° 34' N., 72° 10' W.|S. of New York. |
| 50. | " 21|42° 8' N., 63° 39' W.|S. of Halifax. |
| 64. |June 20|35° 35' N., 50° 27' W.| (Ocean). |
| 76. |July 3|38° 11' N., 27° 9' W.|Azores. |
| | | | |
| 98. |Aug. 14| 9° 21' N., 18° 28' W.|W. of Sierra Leone. |
| 106. | " 25| 1° 47' N., 24° 26' W.| (Ocean). |
| 108. | " 27| 1° 10' N., 28° 23' W.| (Ocean). |
| 111. | " 31| 1° 45' S., 30° 58' W.| (Ocean). |
| 120. |Sept. 9| 8° 37' S., 34° 28' W.|Pernambuco. |
| | | | |
| 132. |Oct. 10|35° 25' S., 23° 40' W.|Tristan da Cunha. |
| 134. | " 14|36° 12' S., 12° 16' W.|Tristan da Cunha. |
| 137. | " 23|35° 59' S., 1° 34' E.| (Ocean). |
| 138. | " 25|36° 22' S., 8° 12' E.| (Ocean). |
| 143. |Dec. 19|36° 48' S., 19° 24' E.|Cape of Good Hope. |
| | | | |
| 144. | " 24|45° 57' S., 34° 39' E.| (Ocean). |
| 145. | " 27|46° 43' S., 38° 4' E.|Prince Edward Island. |
| 146. | " 29|46° 46' S., 45° 31' E.| (Ocean). |
| 147. | " 30|46° 16' S., 48° 27' E.|W. of the Crozet Islands. |
| | 1874. | | |
| 148. |Jan. 3|46° 47' S., 51° 37' E.|E. of the Crozet Islands. |
| | | | |
| 149H. | " 29|48° 45' S., 69° 14' E.|Kerguelen Island. |
| 150. |Feb. 2|52° 4' S., 71° 22' E.|N. of Heard Island. |
| 151. | " 7|52° 59' S., 73° 33' E.|Heard Island. |
| 152. | " 11|60° 52' S., 80° 20' E.|(Ocean). |
| 153. | " 14|65° 42' S., 79° 49' E.|Antarctic Ice. |
| | | | |
| 154. | " 19|64° 37' S., 85° 49' E.|Antarctic Ice. |
| 155. | " 23|64° 18' S., 94° 47' E.|Antarctic Ice. |
| 156. | " 26|62° 26' S., 95° 44' E.| (Ocean). |
| 157. |Mar. 3|53° 55' S., 108° 35' E.| (Ocean). |
| 158. | " 7|50° 1' S., 123° 4' E.| (Ocean). |
| | | | |
| 159. | " 10|47° 25' S., 130° 22' E.| (Ocean). |
| 160. | " 13|42° 42' S., 134° 10' E.| (Ocean). |
| 162. |April 2|39° 10' S., 146° 37' E.|Bass Strait. |
| 163. | " 4|36° 57' S., 150° 34' E.|Port Jackson. |
| 164A. |June 13|34° 9' S., 151° 55' E.|W. of Sydney. |
| | | | |
| 165. | " 17|34° 50' S., 155° 28' E.| (Ocean). |
| 166. | " 23|38° 50' S., 169° 20' E.|W. of New Zealand. |
| 169. |July 10|37° 34' S., 179° 22' E.|E. of New Zealand. |
| 175. |Aug. 12|19° 2' S., 177° 10' E.|Fiji Islands. |
| 181. | " 25|13° 50' S., 151° 49' E.|Louisiades. |
| | | | |
| 193. |Sept. 28| 5° 24' S., 130° 37' E.|Banda Sea. |
| 195. |Oct. 3| 4° 21' S., 129° 7' E.|Banda Sea. |
| 197. | " 14| 0° 41' N., 126° 37' E.|E. of Celebes. |
| 198. | " 20| 2° 55' N., 124° 58' E.|N. of Celebes. |
| 200. | " 23| 6° 47' N., 122° 28' E.|W. of Mindanao. |
| | | | |
| 201. | " 26| 7° 3' N., 121° 48' E.|W. of Mindanao. |
| 202. | " 27| 8° 32' N., 121° 55' E.|W. of Mindanao. |
| 205. |Nov. 13|16° 42' N., 119° 22' E.|W. of Luzon. |
| | 1875. | | |
| 206. |Jan. 8|17° 54' N., 117° 14' E.|W. of Luzon. |
| 211. | " 28| 8° 0' N., 121° 42' E.|W. of Mindanao. |
| | | | |
| 213. |Feb. 8| 5° 47' N., 124° 1' E.|S. of Mindanao. |
| 214. | " 10| 4° 33' N., 127° 6' E.|N. of Gilolo. |
| 215. | " 12| 4° 19' N., 130° 15' E.|N. of Gilolo. |
| 216A. | " 16| 2° 56' N., 134° 11' E.|S. of Pelew Islands. |
| 217. | " 22| 0° 39' S., 138° 55' E.|N. of New Guinea. |
| | | | |
| 218. |Mar. 1| 2° 33' S., 144° 4' E.|N. of New Guinea. |
| 220. | " 11| 0° 42' S., 147° 0' E.|N. of New Guinea. |
| 221. | " 13| 0° 40' N., 148° 41' E.| (Ocean). |
| 222. | " 16| 2° 15' N., 146° 16' E.| (Ocean). |
| 223. | " 19| 5° 31' N., 145° 13' E.|Carolines. |
| | | | |
| 224. | " 21| 7° 45' N., 144° 20' E.|Carolines. |
| 225. | " 23|11° 24' N., 143° 16' E.|Ocean } |
| 226. | " 25|14° 44' N., 142° 13' E.|Ocean } North-West Pacific,|
| 230. |April 5|26° 29' N., 137° 57' E.|Ocean } between Carolines |
| 231. | " 9|31° 8' N., 137° 8' E.|Ocean } and Japan. |
| | | | } |
| 232. |May 12|35° 11' N., 139° 28' E.|Ocean } |
| 234. |June 3|32° 31' N., 135° 39' E.|S. of Japan. |
| 235. | " 4|34° 7' N., 138° 0' E.|S. of Japan. |
| 236. | " 5|34° 58' N., 139° 29' E.|S. of Japan. |
| 237. | " 17|34° 37' N., 140° 32' E.|S. of Japan. |
| | | | |
| 238. | " 18|35° 18' N., 144° 8' E.|Ocean } |
| 239. | " 19|35° 18' N., 147° 9' E.|Ocean } |
| 240. | " 21|35° 20' N., 153° 39' E.|Ocean } |
| 241. | " 23|35° 41' N., 157° 42' E.|Ocean } |
| 242. | " 24|35° 29' N., 161° 52' E.|Ocean } |
| | | | } |
| 243. | " 26|35° 24' N., 166° 35' E.|Ocean } North Pacific, |
| 244. | " 28|35° 22' N., 169° 53' E.|Ocean } between Japan and |
| 245. | " 30|36° 23' N., 174° 31' E.|Ocean } San Francisco |
| 246. |July 2|36° 10' N., 178° 0' E.|Ocean } (35°-38° N. lat., |
| 247. | " 3|35° 49' N., 179° 57' W.|Ocean } 144°-156° W. long.)|
| | | | } |
| 248. | " 5|37° 41' N., 177° 4' W.|Ocean } |
| 249. | " 7|37° 59' N., 171° 48' W.|Ocean } |
| 250. | " 9|37° 49' N., 166° 47' W.|Ocean } |
| 251. | " 10|37° 37' N., 163° 26' W.|Ocean } |
| 252. | " 12|37° 52' N., 160° 17' W.|Ocean } |
| | | | } |
| 253. | " 14|38° 9' N., 156° 25' W.|Ocean |
| 254. | " 17|35° 13' N., 154° 43' W.|Ocean } |
| 255. | " 19|32° 28' N., 154° 33' W.|Ocean } North Pacific |
| 256. | " 21|30° 22' N., 154° 56' W.|Ocean } (35°-23° N. lat., |
| 257. | " 23|27° 33' N., 154° 55' W.|Ocean }154°-156° W. long.).|
| | | | } |
| 258. | " 24|26° 11' N., 155° 12' W.|Ocean } |
| 259. | " 26|23° 3' N., 156° 6' W.|Ocean } |
| 261. |Aug. 12|20° 18' N., 157° 14' W.|Sandwich Islands. |
| 262. | " 20|19° 12' N., 154° 14' W.|Sandwich Islands. |
| 263. | " 21|17° 33' N., 153° 36' W.|Ocean } |
| | | | } |
| 264. | " 23|14° 19' N., 152° 37' W.|Ocean } |
| 265. | " 25|12° 42' N., 152° 1' W.|Ocean } |
| 266. | " 26|11° 7' N., 152° 3' W.|Ocean } Tropical Central |
| 267. | " 28| 9° 28' N., 150° 49' W.|Ocean } Pacific, between |
| 268. | " 30| 7° 35' N., 149° 49' W.|Ocean } Sandwich and |
| | | | } |
| 269. |Sept. 2| 5° 54' N., 147° 2' W.|Ocean } Paumotu |
| 270. | " 4| 2° 34' N., 149° 9' W.|Ocean } (17° N. lat. to |
| 271. | " 6| 0° 33' S., 151° 34' W.|Ocean } 11° S. lat.). |
| 272. | " 8| 3° 48' S., 152° 56' W.|Ocean } |
| 273. | " 9| 5° 11' S., 152° 56' W.|Ocean } |
| | | | } |
| 274. | " 11| 7° 25' S., 152° 15' W.|Ocean } |
| 275. | " 14|11° 20' S., 150° 30' W.|Ocean } |
| 276. | " 16|13° 28' S., 149° 30' W.|Paumotu. |
| 280. |Oct. 4|18° 40' S., 149° 52' W.|S. of Tahiti. |
| 281. | " 6|22° 21' S., 150° 17' W.|Tubuai Islands. |
| | | | |
| 282. | " 7|23° 46' S., 149° 59' W.|Tubuai Islands. |
| 283. | " 9|26° 9' S., 145° 17' W.|N. of Oparo Island. |
| 284. | " 11|28° 22' S., 141° 22' W.|S. of Oparo Island. |
| 285. | " 14|32° 36' S., 137° 43' W.|Ocean } |
| 286. | " 16|33° 29' S., 133° 22' W.|Ocean } |
| | | | |
| 287. | " 10|36° 32' S., 132° 52' W.|Ocean } |
| 288. | " 21|40° 3' S., 132° 58' W.|Ocean } |
| 289. | " 23|39° 41' S., 131° 23' W.|Ocean } |
| 290. | " 25|39° 16' S., 124° 7' W.|Ocean } Open South Pacific |
| 291. | " 27|39° 13' S., 118° 49' W.|Ocean } Ocean, between New |
| | | | } Zealand and |
| 292. | " 29|38° 43' S., 112° 31' W.|Ocean } Valparaiso. |
| 293. |Nov. 1|39° 4' S., 105° 5' W.|Ocean } |
| 294. | " 3|39° 22' S., 98° 46' W.|Ocean } |
| 295. | " 5|38° 7' S., 94° 4' W.|Ocean } |
| 296. | " 9|38° 6' S., 88° 2' W.|Ocean } |
| | | | } |
| 297. | " 11|37° 29' S., 83° 7' W.|Ocean } |
| 298. | " 17|34° 7' S., 73° 56' W.|W. of Valparaiso. |
| 299. |Dec. 14|33° 31' S., 74° 43' W.|W. of Valparaiso. |
| 300. | " 17|33° 42' S., 78° 18' W.|N. of Juan Fernandez. |
| 302. | " 28|42° 43' S., 82° 11' W.| (Ocean). |
| | | | |
| 303. | " 30|45° 31' S., 78° 9' W.|W. of Patagonia. |
| 304. | " 31|46° 53' S., 75° 12' W.|W. of Patagonia. |
| | 1876. | | |
| 318. |Feb. 11|42° 32' S., 56° 29' W.| (Ocean). |
| 319. | " 12|41° 54' S., 54° 48' W.| (Ocean). |
| 323. | " 28|35° 39' S., 50° 47' W.|W. of Buenos Ayres. |
| | | | } |
| 324. | " 29|36° 9' S., 48° 22' W.|Ocean } |
| 325. |Mar. 2|36° 44' S., 46° 16' W.|Ocean } |
| 326. | " 3|37° 3' S., 44° 17' W.|Ocean } Open South Atlantic|
| 327. | " 4|36° 48' S., 42° 45' W.|Ocean } Ocean, between |
| 328. | " 6|37° 38' S., 39° 36' W.|Ocean } Buenos Ayres and |
| | | | } |
| 329. | " 7|37° 31' S., 36° 7' W.|Ocean } Tristan da Cunha |
| 330. | " 8|37° 45' S., 33° 0' W.|Ocean } (35°-37° S. lat., |
| 331. | " 9|37° 47' S., 30° 20' W.|Ocean } 21°-48° W. long.). |
| 332. | " 10|37° 29' S., 27° 31' W.|Ocean } |
| 333. | " 13|35° 36' S., 21° 12' W.|Ocean } |
| | | | |
| 334. | " 14|35° 45' S., 18° 31' W.|W. of Tristan da Cunha. |
| 335. | " 16|32° 24' S., 13° 5' W.|N. of Tristan da Cunha. |
| 338. | " 21|21° 15' S., 14° 2' W.|(Ocean). |
| 340. | " 24|14° 33' S., 13° 42' W.|Ocean } |
| 341. | " 25|12° 16' S., 13° 44' W.|Ocean } W. of St. Helena. |
| | | | |
| 342. | " 26| 9° 43' S., 13° 51' W.|Ocean } |
| 343. | " 27| 8° 3' S., 14° 27' W.|Ascension Island. |
| 344. |April 3| 7° 54' S., 14° 28' W.|Ascension Island. |
| 345. | " 4| 5° 45' S., 14° 25' W.|Ocean } |
| 346. | " 6| 2° 42' S., 14° 41' W.|Ocean } Tropical Atlantic, |
| | | | } between Ascension |
| 347. | " 7| 0° 15' S., 14° 25' W.|Ocean } and Sierra Leone. |
| 348. | " 9| 3° 10' N., 14° 51' W.|Ocean } |
| 349. | " 10| 5° 28' N., 14° 38' W.|Ocean } |
| 350. | " 11| 7° 33' N., 15° 16' W.|W. of Sierra Leone. |
| 351. | " 12| 9° 9' N., 16° 41' W.|W. of Sierra Leone. |
| | | | |
| 352. | " 13|10° 55' N., 17° 46' W.|W. of Sierra Leone. |
| 353. |May 3|26° 21' N., 33° 37' W.|W. of Canary Islands. |
| 354. | " 6|32° 41' N., 36° 6' W.|S. of Azores. |
+----------+--------+-----------------------+---------------------------+
{clxiv}CHAPTER X.--GEOGRAPHICAL DISTRIBUTION.
(§§ 241-250.)
241. _Historical Distribution._--Radiolaria are found fossil in all the
more important groups of the sedimentary rocks of the earth's crust. Whilst
a few years ago their well-preserved siliceous skeletons were only known in
considerable quantity from Cainozoic marls (§ 242), very many SPUMELLARIA
and NASSELLARIA have recently been found in Mesozoic and a few in Palæozoic
strata. By the aid of improved modern methods of investigation (especially
by the preparation of thin sections of very hard rocks) it has been shown
that many hard siliceous minerals, especially cryptocrystalline quartz,
contain numerous well-preserved Radiolaria, and sometimes are mainly
composed of closely compacted masses of such siliceous shells; of this kind
are many quartzites of the Jura (§ 243). These Jurassic quartzes
(Switzerland), as well as the Tertiary marls (Barbados) and clays (Nicobar
Islands), are to be regarded as "fossil Radiolarian ooze" (§ 237). Dense
masses of compressed SPUMELLARIA and NASSELLARIA form the principal part of
these rocks. Isolated or in smaller quantities, fossil Polycystina,
belonging to different families of SPUMELLARIA and NASSELLARIA, also occur
in in other rocks, and even in some of Palæozoic origin. Since specimens
have also been recently found both in Silurian and Cambrian strata, it may
be stated that as regards their historical distribution, Radiolaria occur
in all fossiliferous sedimentary deposits, from the oldest to those of the
present time.
242. _Cainozoic Radiolaria._--The great majority of fossil Radiolaria which
have hitherto been described, belong to the Cainozoic or Tertiary period,
and in fact, to its middle portion, the Miocene period. At this period the
richest and most important of all the Radiolarian formations were
deposited, such as the pure "Polycystine marl" of Barbados (see note A),
also that of Grotte in Sicily (see note B), and the clay of the Nicobar
Islands (see note C). Besides the above-mentioned deposits, which may be
designated "pure" fossil Radiolarian ooze, many deposits containing these
organisms have recently been discovered in widely separated parts of the
earth, partly of the nature of tripoli or marl, partly resembling clay.
Among these may be mentioned in the first place many coasts and islands of
the Mediterranean, both on the south coast of Europe (Sicily, Calabria,
Greece), and the north coast of Africa (from Oran to Tripoli). The
extensive layers of tripoli which are found in these Mediterranean Tertiary
mountains belong to the upper Miocene (Tortona stage), and consist partly
of marl rich in calcareous matter, and resembling chalk, partly passing
over into plastic clay or "Kieselguhr" (§ 246). The quantity of Radiolaria
contained varies, and is more conspicuous the fewer the calcareous shells
of Foraminifera present. Similar Tertiary Polycystine formations occur in
some parts of America (see note D); probably they have a very wide
distribution. In their general morphological characters, the Tertiary
SPUMELLARIA and NASSELLARIA {clxv}are related to those forms which are
found in the recent Radiolarian ooze of the depths of the Pacific,
especially to the species which are characteristic of the Challenger
Stations 225, 226, 265 and 268. Many living genera and families (_e.g._,
most #Larcoidea# and #Stephoidea#) have not yet been found in the Tertiary
formations.
A. The famous Polycystine marl of Barbados in the Antilles, which Robert
Schomburgk discovered forty years ago, belongs to the Miocene formation,
and is the richest and best known of all the important Radiolarian
deposits (see L. N. 16, pp. 5-8). After Ehrenberg had published in
December 1846 the first preliminary communication regarding its
composition out of masses of well-preserved Polycystina, he was able in
the following year to describe no less than 282 species from it; he
distributed these in 44 genera and 7 families (L. N. 4, 1847, p. 54). In
the year 1854 Ehrenberg published figures of 33 species in his
Mikrogeologie (L. N. 6, Taf. xxxvi.); but it was only in 1873 that he
published descriptions of 265 species (Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, Jan. 30, pp. 213-263). Finally there followed in 1875 his
Fortsetzung der Mikrogeologischen Studien, mit specieller Rücksicht auf
den Polycystinen-Mergel von Barbados (L. N. 25). On the thirty plates
which accompany this the last work of Ehrenberg, 282 species are figured
and named, of which 54 are SPUMELLARIA (13 #Sphæroidea#, 8 #Prunoidea#,
33 #Discoidea#), and 228 NASSELLARIA (2 #Stephoidea#, 38 #Spyroidea#, and
188 #Cyrtoidea#). The fourth section of this memoir contains a survey of
the Polycystine formation of Barbados (pp. 106-115), and the fifth
section the special description of a large specimen of rock from Mount
Hillaby in Barbados (see also L. N. 28, p. 117, and L. N. 41, pp.
476-478). The account given by Ehrenberg of the Polycystina of Barbados
is in many respects very incomplete, and very far from exhausting this
rich mine of remarkable forms. This may be readily seen from the
twenty-five plates of figures of Polycystins in the Barbados Chalk
Deposit published by Bury in 1862 (L. N. 17). The number of species here
figured (140 to 142) is about half of those given by Ehrenberg; and there
are among them numerous generic types, some of great interest, which were
entirely overlooked by the latter; _e.g._ _Saturnalis_ (#Sphæroidea#),
_Cannartidium_ (#Prunoidea#), _Tympanidium_ (#Stephoidea#),
_Cinclopyramis_ (#Cyrtoidea#), &c. Finally, Ehrenberg always (until 1875)
ignored Bury's atlas, which had been published thirteen years ago and was
quite accessible to him. How different were the contents of the two works
may easily be seen from the following abstract.
_Comparative View of the Species of Fossil Radiolaria from Barbados made
known by the figures of Bury in 1862 and of Ehrenberg in 1875._
+-------------------+--------------------+--------+-----------+-------+
| Legion. | Order. | Bury. | Ehrenberg.| Total.|
+-------------------+--------------------+--------+-----------+-------+
| I. Legion | { 1. Sphæroidea | 16 | 13 | 29 |
| SPUMELLARIA | { 2. Prunoidea | 10 | 8 | 18 |
| (PERIPYLEA). | { 3. Discoidea | 37 | 33 | 70 |
| | | | | |
| II. Legion | { 4. Stephoidea | 5 | 2 | 7 |
| NASSELLARIA | { 5. Spyroidea | 13 | 38 | 51 |
| (MONOPYLEA). | { 6. Cyrtoidea | 60 | 188 | 248 |
+-------------------+--------------------+--------+-----------+-------+
| Total, | 141 | 282 | 423 |
+----------------------------------------+--------+-----------+-------+
{clxvi}In 1882 Bütschli still further increased the number of known
Radiolaria from Barbados both by figures and descriptions (L. N. 40), and
gave in particular a very accurate morphological analysis of 12 new
NASSELLARIA (3 #Stephoidea#, 3 #Spyroidea#, and 6 #Cyrtoidea#; L. N. 40,
Taf. xxxii., xxxiii.). The number of the fossil species collected in the
Barbados marl is, however, greater than would appear from the
above-quoted communications. My respected friend, Dr. R. Teuscher, of
Jena, has, at my request, made a large number (about a thousand) of very
accurate drawings with the camera lucida of Polycystina from Barbados
(see p. 1760). From these it appears that the variations in the structure
of the shells, with respect to number, size, and form of the
lattice-pores, of the spines, &c., is much greater than would be supposed
from the figures of Ehrenberg and Bury. I have thus come to the
conviction that the number of species from Barbados (using the word
"species" in the sense understood by those authors) is not less than 400
and probably more than 500. Descriptions of some particularly interesting
new species from this series have been included in the systematic account
of the Challenger Radiolaria. A complete critical investigation of the
Radiolaria of Barbados, and especially an accurate comparison of these
Cainozoic species with the Mesozoic forms from the Jura, on the one hand,
and with recent types on the other, must be left to the future for its
accomplishment (see § 246).
B. The Cainozoic Polycystine tripoli or marl of the Mediterranean coast,
which is probably always of Miocene origin, forms very extensive mountain
ranges both in the south of Europe (Sicily, Calabria, Greece) and in the
north of Africa (from Oran to Tripoli) (§ 246). Hitherto, however, only
one locality has been thoroughly investigated, namely, Grotte in the
province of Girgenti in Sicily (L. N. 35). In the accurate account which
was given of it by Stöhr in 1880, 118 species were described, distributed
in 40 genera (L. N. 35; pp. 72-84); of these 118 species 78 are quite
new, 25 are identical with previously known fossils, and 29 identical
with living forms. Among them are 73 SPUMELLARIA (28 #Sphæroidea#, 8
#Prunoidea#, and 37 #Discoidea#), but only 40 NASSELLARIA (1
#Stephoidea#, 6 #Spyroidea#, and 33 #Cyrtoidea#), and 5 PHÆODARIA
(Dictyochida). The other parts of Sicily from which the same upper
Miocene tripoli has been investigated (belonging to the Tortona stage)
have proved less rich than Grotte. The best known of these places is
Caltanisetta, since upon three genera discovered here (_Haliomma_,
_Cornutella_, _Lithocampe_) the group Polycystina was founded by
Ehrenberg in 1838 (see L. N. 16, p. 3). Afterwards 31 species were
described from this locality, of which 23 were again found in Grotte. The
richest deposit on the Mediterranean coast, however, appears to be at
Oran. A small specimen of the Kieselguhr found there, which was recently
sent to me by Professor Steinman, proved to be pure Radiolarian ooze,
very similar to that now found in the Central Pacific, and contained many
hitherto undescribed species; it is deserving of careful investigation
and comparison.
C. Regarding the Tertiary Radiolarian clay of the Nicobar Islands, see §
247 and L. N. 25, pp. 116-120. Its fauna is incompletely known; probably
it is of Miocene or Oligocene origin.
D. Cainozoic tripoli, containing larger or smaller quantities of
Radiolaria, appears to be rather widely distributed in America. Ehrenberg
has described such from South America (polishing-slate from Morro di
Mijellones, on the coast between Chili and Bolivia), and from North
America (Richmond and Petersburg in Virginia, Piscataway in Maryland).
Similar deposits are also found in the Bermuda Islands (L. N. 4, 1855-56;
L. N. 6, Taf. 18; L. N. 16, pp. 3-9; L. N. 41, pp. 475-478, and L. N. 25,
pp. 2-6).
{clxvii}243. _Mesozoic Radiolaria._--From the Mesozoic or Secondary period
numerous well-preserved Radiolaria have recently been described. They
belong for the most part to the Jurassic formation (see notes A, B, C),
whilst the more recent Chalk (see note D) and the older Trias (see note E)
have hitherto yielded but few species. All the main divisions of the Jura,
both the upper (Malm) and the middle (Dogger), and especially the lower
(Lias) appear in certain localities to be very rich in well-preserved
shells of fossil Polycystina. Most of these are aggregated together in
coprolites and quartzites (jasper, chert, flint, &c., § 248). The majority
are #Cyrtoidea#, the minority #Sphæroidea# and #Discoidea# in almost equal
proportions; a few #Beloidea# (_Sphærozoum_) and #Phæocystina# (Dictyocha)
are also found among them. The general morphological character of these
Jurassic Radiolaria is very different from that of the nearly related
Tertiary and living forms. In general, their siliceous shells are firmer
and more massive, usually also somewhat larger, but of simpler structure.
The manifold delicate appendages (spines, bristles, feet, wings, &c.) which
are so richly developed in the living SPUMELLARIA and NASSELLARIA, and are
also well shown in the Tertiary species, are entirely wanting in the
majority of the Jurassic Polycystina. The #Sphæroidea# and #Prunoidea# are
all simple spherical or ellipsoidal lattice-shells (Monosphærida);
concentric lattice-shells (Polysphærida) are entirely wanting. The
#Cyrtoidea# are, for the most part, devoid of radial processes or basal
feet (Eradiata); triradiate and multiradiate forms, such as are found
abundantly in the recent and Tertiary formations, are very rare. The large
number of many-jointed forms (Stichocyrtida) and of #Cyrtoidea# with
latticed basal opening is very striking.
A. The most important work on the Jurassic Radiolaria, regarding which
but little was known prior to the year 1885, is the valuable and in some
respects very interesting Beiträge zur Kenntniss der fossilen Radiolarien
aus Gesteinen des Jura, by Dr. Rüst of Freiburg i. B. (1885,
Palæontographica, Bd. xxxi. 51 pp. with 12 plates). Unfortunately this
important work was issued only when about half of the present Report was
printed off, so that it was no longer possible to include the 234 species
there described in its systematic part. I have therefore elsewhere given
a list of the Jurassic Radiolaria, and at present only make the following
remarks:--Of the 234 species described, the larger half (130) belong to
the NASSELLARIA (#Cyrtoidea#), the smaller half (102) to the SPUMELLARIA
(38 #Sphæroidea#, 14 #Prunoidea#, and 50 #Discoidea#). In addition, there
are 2 PHÆODARIA depicted, and several spicules which are probably to be
referred to the #Beloidea#. Among the 130 #Cyrtoidea# (of which 2 are
described as #Botryodea#), there are 24 Monocyrtida, 14 Dicyrtida, 22
Tricyrtida, and 70 Stichocyrtida. Just as striking as the predominant
number of the last is the fact that there are only very few triradiate
(9) and multiradiate (4) species found among these 130 #Cyrtoidea#, as
also the large number of species with latticed basal opening;
#Stephoidea# appear to be entirely wanting. The rich material of jasper,
chert, flint, and coprolites in which Dr. Rüst found these Radiolaria, is
derived for the most part from the Jurassic rocks of Germany (Hanover,
South Bavaria), Tyrol, and Switzerland (compare § 248).
{clxviii}B. Jurassic Radiolaria from Italy, also found in jasper, which
are closely related to the forms from Germany and Switzerland described
by Dr. Rüst, were made known so long ago as 1880 by Dante Pantanelli in
his treatise I Diaspri della Toscana e i loro Fossili (Rome, 1880, 33 pp.
60 figs.). Pantanelli believes, however, that this jasper is for the most
part of Eocene origin; but from his description, and especially from the
morphological character of the forms which he figures, it appears very
probable "that these Tuscan jaspers from Galestro, like those of the
Swiss conglomerates, are found in a secondary locality and belong to the
Jurassic period" (Rüst, L. N. 51, p. 3). Unfortunately the figures of
Pantanelli are so small and incomplete that a reliable determination of
the species is hardly possible; for example, the lattice-work is only
given in ten of the sixty figures. Among the 32 recorded species 15 are
SPUMELLARIA (6 #Sphæroidea# and 9 #Discoidea#) and 17 NASSELLARIA (4
#Stephoidea# and 13 #Cyrtoidea#); many of which seem to be identical with
the forms more accurately described by Dr. Rüst (compare p. 1762).
C. From the Lias of the Alps and more particularly "from the lower
Liassic beds of the Schafberg near Salzburg," Dr. Emil von Dunikowski in
1882 described 18 species of fossil Radiolaria (L. N. 44, pp. 22-34, Taf.
iv.-vi.); most of these are #Sphæroidea# and #Discoidea# and appear to
have been more or less altered by petrological changes; their spongy
structure is probably secondary.
D. Cretaceous Radiolaria have been hitherto described only in very small
numbers; quite recently Dr. Rüst has found a larger number chiefly in
flints from the English chalk, but they have not yet been published. In
1876 Zittel described 6 very well-preserved species from the upper chalk
of North Germany (L. N. 29, pp. 76-96, Taf. ii.); among them were 1
#Sphæroidea#, 1 #Discoidea#, 1 Dictyocha, and 3 #Cyrtoidea#.
E. Triassic Radiolaria have recently been discovered by Dr. Rüst in
chert, but have not yet been described.
244. _Palæozoic Radiolaria._--The number of Radiolaria which are known from
the Palæozoic or Primary formations is much less than from either the
Mesozoic or Cainozoic periods. Here, however, the investigations of recent
times have yielded important information; a few species, at all events, of
Polycystina (mostly #Sphæroidea#) are now known from various Palæozoic
formations, and not only from the Permian ("Zechstein") and the
Coal-measures, but also from the older Devonian and Silurian systems. Even
in the still older Cambrian rocks a few fossil Radiolaria have been found.
All these Palæozoic Radiolaria are Polycystina of very simple form and
primitive structure, mostly simple SPUMELLARIA (latticed spheres,
ellipsoids, lenses, &c.), but partly also simple NASSELLARIA.
The important discoveries which have recently been made by Dr. Rüst
regarding the occurrence of Radiolaria in all the Palæozoic formations
have not yet been published. From conversations with this estimable
palæontologist I have learned, however, that he has pursued his fruitful
investigation of the Mesozoic quartzites (§ 243), and has met with no
less success in the case of similar Palæozoic structures. Although the
number of species hitherto discovered is relatively small, the important
conclusion appears to be warranted that they extend as far as the
Silurian and Cambrian systems. All these very ancient SPUMELLARIA
(#Sphæroidea#) and NASSELLARIA (#Cyrtoidea#) {clxix}exhibit very
primitive structural relations. The occurrence of fossil Polycystina in
the Carboniferous formation of England has been incidentally mentioned by
W. J. Sollas:--"In the carboniferous beds of North Wales pseudomorphs of
Radiolaria in calcite occur, along with minute quartz crystals" (Ann. and
Mag. Nat. Hist., 1880, ser. 5, vol. vi. p. 439); and in the siliceous
slate-beds of Saxony Rothpletz has shown the existence of a few
#Sphæroidea# (Zeitschr. d. Deutsch. Geol. Gesellsch., 1800, p. 447).
245. _Abundance of Radiolaria in the Various Rocks._--The relative quantity
of well-preserved or at all events recognisable Radiolaria in the different
rocks is very variable. In this respect three different degrees may be
distinguished, which may be called shortly "pure, mixed, and poor"
Radiolarian formations. The _pure_ Radiolarian rocks consist for the
greater part (usually much more than half, sometimes even more than
three-quarters) of closely compacted often calcined masses of siliceous
Polycystine shells. To this category belong the pure Miocene Polycystine
marls of Barbados (§ 246), the Tertiary Polycystine clay of the Nicobar
Islands (§ 247), and the Polycystine quartz of the Jura (§ 248). All these
pure Radiolarian rocks may be regarded as fossil Radiolarian ooze (§ 237),
and are certainly of deep-sea origin, having probably been deposited at
depths greater than 2000 fathoms. Their palæontological character also is
in favour of this view, for the abyssal Osculosa (§ 235) are more abundant
and richer in species than the pelagic Porulosa (§ 233). The elevation of
this deep-sea layer above the surface of the sea appears to have taken
place but seldom; it has only been observed on a large scale at Barbados
and in the Nicobar Islands. The _mixed_ Radiolarian rocks are much more
common; they were probably deposited at much less depths, or perhaps are
not true deep-sea formations at all. The siliceous shells of Polycystina
always constitute less than half (sometimes less than one-tenth) of their
mass, and are less prominent than other siliceous remains (Diatoms), or
calcareous remains (Foraminifera), or in some cases than the mineral
constituents (pumice, &c.). To this group belong many of the
above-mentioned Tertiary marls and clays (especially the Mediterranean
Tripoli), also many flints, cherts, and other quartzites from Mesozoic
strata (especially from the Jura), and probably also some palæozoic
quartzites. The marine ooze from which they have originated may have been
deposited at very various, even at slight, depths of the ocean. Formations
_poor_ in Radiolaria, which contain only a few species of SPUMELLARIA and
NASSELLARIA mingled with other fossil remains and mineral particles, occur
in all formations and are probably very widely distributed. Further careful
examination of thin sections (especially of coprolites) will yield here a
rich harvest of new forms. Both the mixed and the pure Radiolarian
formations may be divided according to their petrographic characters into
three groups, which, however, are connected by intermediate varieties--(1)
soft, chalky marl (§ 246), (2) plastic clay (§ 247), and (3) hard, flinty
quartz (§ 248).
{clxx}246. _Radiolarian Marl._--Those soft, friable rocks, which contain a
large quantity of calcareous matter, but consist for the most part of the
shells of SPUMELLARIA and NASSELLARIA, are called Radiolarian or
Polycystine marl, often more correctly Polycystine tripoli; the best known
example of them is the chalky marl of Barbados in the Antilles (§ 242). The
Tertiary mountain system of this island, which in Mount Hillaby rises to a
height of 1147 feet and includes about 15,800 acres, consists almost
exclusively of these remarkable masses of rock. Most of it appears as a
soft, earthy, often chalky marl, with a considerable but variable amount of
calcareous matter. Those specimens, the greater half of which is composed
of well-preserved siliceous shells of Polycystina, and which contain little
lime, approach the tripoli and "Kieselguhr." Those specimens, however,
which contain the largest amount of calcareous matter resemble common
writing chalk in consistency, and consist for the most part of shells of
Foraminifera and their fragments; of these there are only few species but
large numbers of individuals, generally in small fragments with a fine
calcareous powder between them. They may be regarded as fossil Globigerina
ooze (§ 238). In a third group of specimens from Barbados the quantity of
fragments of pumice and other volcanic matters predominates; the amount of
clay is also very considerable; these deposits pass over partly into actual
clay partly into volcanic tuff. A fourth group exhibits relations to a
coarser often ferruginous material, and although the shells of Polycystina
are less abundant in it, still it may be shown to be composed largely of
fragments and metamorphosed remains of them. The colour of this deposit,
which in some places passes over into sandstone, in others into clay, is
usually rather dark, grey, brown, sometimes red and occasionally black
(bituminous). The Radiolarian marls of the first two groups, which
sometimes approach the white chalk, sometimes the Kieselguhr, are grey, or
even pure white (see note A). The same constitution is exhibited by the
yellowish or white, very light and friable Polycystine marls of Sicily,
which in Caltanisetta approach the chalk, and in Grotte the Kieselguhr. In
Greece (Ægina, Zante, &c.), on the other hand, they pass over into plastic
clay, and the same occurs in the Baden marl of the Vienna basin. In North
Africa, however, on the Mediterranean shores of which the Radiolarian marl
seems to be very widely distributed (from Tripoli to Oran), it sometimes
becomes changed into actual firm polishing slate, sometimes into
pulverulent Kieselguhr or tripoli (Terra tripolitana, see note B). Most of
these Radiolarian marls appear to date from the middle Tertiary (Miocene)
period, and to be deep-sea formations.
A. The Polycystine marl of Barbados appears at different parts of the
island to present greater variations in its petrographical and
zoographical composition than would appear from Ehrenberg's description
(1875, L. N. 25, pp. 106-116). Through the kindness of one of my former
students, Dr. Dorner, to whom I take this opportunity of expressing my
thanks for the favour, I received a large number of specimens of Barbados
rock, taken from various parts of the island, and they exhibit very great
variations in their external appearance, their chemical composition, and
the {clxxi}Radiolaria which they contain. The white specimens resembling
Kieselguhr contained approximately 60 to 70 per cent. by volume of
Radiolarian shells, the yellowish marl 40 to 50 per cent., and the brown
and black (bituminous) marl 10 to 20 per cent. or less. Two analyses of
the first, which my friend Dr. W. Weber was good enough to carry out,
yielded different results from those which are given by Ehrenberg on the
basis of Rammelsberg's analyses (L. N. 25, p. 116). The results of both
are here given for comparison.
--------------------------------+--------------------------+-------------
Ehrenberg-Rammelsberg | Weber I. | Weber II.
(Fragment from Hillaby). | (Chalk-like Fragment). |(Tripoli-like
| | Fragment).
--------------------------------+--------------------------+-------------
Silicate of alumina, 59.47 |Silica, 52.2 | 71.3
Alumina and oxide of iron, 1.95 |Alumina (with traces |
Calcium carbonate, 34.31 | of oxide of iron), 12.3 | 11.2
Water, 3.67 |Lime and magnesia, 31.9 | 14.8
|Carbon dioxide, 3.2 | 2.7
______ | _____ | _____
Total, 99.40 | Total, 99.6 | 100.0
--------------------------------+--------------------------+-------------
For further comparison I here add the three different analyses of Miocene
Tripoli-marls from Sicily, given by Stöhr on the authority of Fremy,
Schwager, and Mottura (Tagebl. d. fünfzigsten Versamml. Deutsch. Naturf.
u. Aertzte in München, 1877, p. 163).
--------------------------+-------------+--------------+-------------
Composition. |Tripoli from | Tripoli from | Tripoli from
| Licata | Grotte | Caltanisetta
| (Fremy). | (Schwager). | (Mottura).
--------------------------+-------------+--------------+-------------
Silica, | 30.98 | 58.58 | 68.6
Alumina, | 17.54 | 11.51 | }
Oxide of iron, | 0.33 | 1.84 | } 3.6
| | |
Lime, } | 38.09 | { 8.49 | }
Magnesia, } | | { 0.41 | } 12.1
| | |
Water and organic matter,}| | { 11.26 | }
Carbonic acid, }| 13.06 | { 7.12 | } 15.2
+-------------+--------------+------------
| 100.00 | 99.21 | 99.5
--------------------------+-------------+--------------+-------------
B. The Radiolarian marl of the Mediterranean appears, judging by the
accounts already published, to stretch along a considerable part of the
coast in the earlier and middle Tertiary formations; thus it occurs of
similar composition in widely separated localities, in Sicily, Calabria,
Zante, and Greece; in North Africa from Tripoli to Oran and probably much
farther. So long ago as 1854 Ehrenberg, in his Mikrogeologie (L. N. 6)
gave a series of important, even if incomplete, communications regarding
the "chalky white calcareous marl of Caltanisetta" (Taf. xxii.), the
"Platten marl of Zante" (Taf. xx.), the "plastic clay of Ægina" (Taf
xix.), and the "polishing slate of Oran" (Taf. xxi.). In 1880 Stöhr
showed in his fundamental description of the Tripoli from {clxxii}Grotte
in Sicily (L. N. 35) that its Radiolarian fauna is much richer than
Ehrenberg supposed. The same is the case in the Tripoli of Caltanisetta,
and also in the Baden marl of the Vienna basin. The richest deposit
appears to be the pure Kieselguhr-like Tripoli from Oran; a small
specimen, which was recently sent to me by Professor Steinmann of
Freiburg, i. B., contained many hitherto undescribed species, and was at
least as rich as the purest Barbados marl.
247. _Radiolarian Clays._--Among the Radiolarian or Polycystine clays we
include the firm, often plastic, formations, which contain a larger
proportion of Radiolaria than of other organic remains. The first of these
to be mentioned is the Cainozoic formation of the Nicobar Islands in
Further India, which rises to a height of 2000 feet above the level of the
sea, and consists for the most part of coloured masses of clay of varying
constitution; on Car Nicobar these are mostly grey or reddish, on the
Island of Camorta they are partly strongly ferruginous and red and yellow
(_e.g._ at Frederickshaven), partly white and light, like meerschaum
(_e.g._ at Mongkata). The latter varieties appear to pass over into pure
loose Polycystine marl like that of Barbados, the former into calcareous
sandstone. Although the Polycystine clays of the Nicobar Islands are as yet
only very incompletely known, it may be concluded with great probability
that they are true deep-sea formations and nearly allied to those recent
forms of red clay, which by their abundance in Radiolaria most nearly
approach the Radiolarian ooze, such for example as the red clay of the
North Pacific between Japan and the Sandwich Islands (Stations 241 to 245,
compare §§ 229 and 239). With this view agrees also the greater or less
quantity of pumice dust and other volcanic products. Probably Radiolarian
clays like those of the Nicobar Islands occur also in other Tertiary rocks;
part of the Barbados marl passes by gradually increasing content of clay
into such; and in this case also the amount of included pumice is often
considerable. Many mixed Radiolarian marls of the Mediterranean (_e.g._, of
Greece and Oran) also appear to pass over at certain points into
Radiolarian clay.
The Radiolarian clays of the Nicobar Islands are unfortunately very
incompletely known both as regards their geological nature and their
palæontological composition. The communications of Rink (Die
Nikobaren-Inseln, eine geographische Skizze, Kopenhagen, 1847) and of
Ehrenberg (L. N. 6, p. 160 and L. N. 25, pp. 116 to 120) leave many
important questions unanswered. The latter has only figured twenty-three
species in his Mikrogeologie (L. N. 6, Taf. xxxvi.). In his tabular list
of names (L. N. 25, p. 120) he only incompletely records thirty-nine
species, although in 1850, immediately after the first examination of the
Nicobar clay, he had distinguished "more than a hundred species, partly
new, partly identical with those of Barbados" (L. N. 16, p. 8). I have
unfortunately been unable in spite of many efforts, to obtain for
investigation a specimen of Nicobar clay. The only microscopical
preparation (from Ehrenberg's collection), which I was able to examine,
contained several hitherto undescribed species. A thorough systematic
examination of these important Radiolarian clays is a pressing necessity,
especially as they seem to be markedly different from those of the
Mediterranean (from Ægina, Zante, &c.).
{clxxiii}248. _Radiolarian Quartzes._--Under the name Radiolarian or
Polycystine quartzes are included those hard, siliceous rocks, which
consist for the most part of the closely compacted shells of SPUMELLARIA
and NASSELLARIA. To these "cryptocrystalline quartzes," or better,
quartzites, belong more especially the pure Radiolarian formations of the
Jura, which have been described as flint, chert, jasper, as well as other
cryptocrystalline quartzites. Most of the rocks of this nature hitherto
examined are from Germany (Hanover, South Bavaria), Hungary, Tyrol, and
Switzerland; others are known from Italy (Tuscany). They occur both in the
upper and middle, but especially in the lower Jurassic formation (also in
the lower layers of the Alpine Lias). A small part of them has been
examined in their primary situation (the red jaspers of Allgäu and Tyrol),
the greater part, however, only as loose rolled stones in secondary
situations (thus in Switzerland in the breccia of the Rigi, in the
conglomerate of the Uetli-Berg, and in many boulders of the Rhine, the
Limmat, the Reuss, and the Aar). The greatest abundance, however, of
Jurassic Radiolaria has been yielded by the silicified coprolites from the
Lias of Hanover. These "Radiolarian coprolites" are roundish or cylindrical
bodies, which may attain the size of a goose-egg; they probably originated
from Fish or Cephalopods, which had fed upon Crustacea, Pteropoda, and
similar pelagic organisms, whose stomachs were already full of Radiolarian
skeletons. Next to the coprolites the richest is the red jasper, whose
colour varies from bright to dark red; it constitutes a true "silicified
deep-sea Radiolarian ooze." The "_Aptychus_ beds" also of South Bavaria and
Tyrol are very rich, and have furnished about one-third of all the
Radiolaria known from the Jura; most of the species too are very well
preserved (compare § 243).
Regarding the remarkable composition and manifold varieties of the
Jurassic Radiolarian quartz, the very full treatise of Dr. Rüst may be
consulted (L. N. 51). The very interesting Radiolarian coprolites, which
that author has discovered in the lower and middle Jura of Hanover, occur
in astonishing numbers in the iron mines at the village of Gross-Ilsede,
four and a half miles south of the town of Peine. They constitute from 2
to 5 per cent. by weight of the Liassic iron ore; of this latter, in the
year 1883 alone, not less than two hundred and eighty million kilograms
were excavated. It is very probable that the careful microscopic
examination of thin sections of coprolites, as well as of flints, chert,
jasper, and other quartzites, would yield a rich harvest of fossil
Radiolaria in other formations also. In Italy Dante Pantanelli has
discovered interesting Polycystine jaspers in Tuscany (L. N. 36, 45);
these also appear to occur in the Jura (compare § 243, and L. N. 51, pp.
3-10).
249. _Fossil Groups._--The preservation of Radiolaria in the fossil state
is, of course, primarily dependent on the composition of their skeleton.
Hence the ACANTHARIA, whose acanthin skeleton although firm is readily
soluble, are never found fossil. The same is true of the skeletons of the
PHÆODARIA, which consist of a silicate of carbon; here, however, a single
exception is found in the Dictyochida, a subfamily of the Cannorrhaphida,
the isolated parts of whose skeletons appear to consist of pure silica, and
{clxxiv}are often found fossil. Of the two other legions those families
which possess no skeleton are of course excluded; the Nassellida among the
NASSELLARIA, and the Thalassicollida and Collozoida among the SPUMELLARIA.
Thus of the 85 known families there remain scarcely 55 of which the
skeletons may be expected in the fossil state; and of these scarcely half
have been actually observed in this condition. Of the 20 orders of this
class enumerated in § 155, the following 9 may be, for palæontological and
geological purposes, completely excluded:--(A) The 4 orders of ACANTHARIA
(1, #Actinelida#; 2, #Acanthonida#; 3, #Sphærophracta#; 4, #Prunophracta#);
(B) 3 orders of PHÆODARIA (5, #Phæosphæria#; 6, #Phæogromia#; 7,
#Phæoconchia#); (C) 1 order of NASSELLARIA (8, #Nassoidea#); (D) 1 order of
SPUMELLARIA (9, #Colloidea#). From a geological point of view the following
6 orders, although occasionally found fossil, are of quite subordinate
importance:--(A) Among the SPUMELLARIA (10, #Beloidea#, and 11,
#Larcoidea#); (B) among the NASSELLARIA (12, #Plectoidea#; 13,
#Stephoidea#; 14, #Botryodea#); (C) among the PHÆODARIA (15, the
#Phæocystina#). On the other hand the following 5 orders, which are the
main constituents of Radiolarian rocks, are of pre-eminent geological
importance:--(A) Among the SPUMELLARIA (16, #Sphæroidea#; 17, #Prunoidea#;
18, #Discoidea#); (B) among the NASSELLARIA (19, #Spyroidea#, and 20,
#Cyrtoidea#). The numerical relation in which the different families of
these orders appear in the Radiolarian formations may be seen on consulting
§ 157.
250. _Fossil and Recent Species._--The fact that there are many Radiolaria
living at the present day, whose shells are found fossil in Tertiary rocks,
is of great phylogenetic and geological significance. This appeared to be
the case even from the older observations upon the Polycystina of the
Barbados marl (see note A), but more recent and extensive observations both
upon these and upon the Miocene Radiolaria of Sicily, have shown that the
number of these "living fossil" forms is much greater than was previously
supposed (see note B). Among the Miocene Radiolaria numerous species, both
of SPUMELLARIA (especially #Sphæroidea# and #Discoidea#) and of NASSELLARIA
(especially #Spyroidea# and #Cyrtoidea#) are not to be distinguished from
the corresponding still living forms (see notes C, D). On the other hand,
those genera, which are rich both in species and individuals (recent as
well as fossil), present continuous series of forms which lead gradually
and uninterruptedly from old Tertiary species to others still living, which
are specifically indistinguishable from them. These interesting
morphological facts are capable of direct phylogenetic application, and
furnish valuable proofs of the truth of the theory of descent.
A. Ehrenberg, in his list of fossil Polycystina (L. N. 25, pp. 64-85,
1875), records 325 species of which 26 are still living.
{clxxv}B. Stöhr, in his list of Miocene Radiolaria from Grotte (L. N. 35,
p. 84, 1880), records 118 species, of which 29 are still living.
C. Teuscher, who at my request has made a large number of comparative
measurements and drawings, both of fossil and living Radiolaria, comes to
the conclusion that numerous SPUMELLARIA and NASSELLARIA from Barbados
are to-day extant and unchanged in the Radiolarian ooze of the deep
Pacific Ocean (compare § 242A, and p. 1760, Note).
D. From the comparative investigations, which I have made during the last
ten years into the recent deep-sea Radiolaria of the Challenger
collection and the Miocene Polycystina of Barbados, it appears that about
a quarter of the latter are identical with living species of the former.
{clxxvi}BIBLIOGRAPHICAL SECTION.