p. 292, below. In its characters this female spider (the male is
unknown) most nearly resembles _N. cæmentaria_, but differs, among
other points, in markings and in having one or more spines on the
genual joint of leg, these spines being almost always absent in the
same joint in _cæmentaria_. The nests of the two species are totally
unlike.]
The hedge-banks near Hyères, and also about the railway station
of the same name, which is some 4 miles from the town itself, are
frequently tenanted by this spider. During a short stay there in
May, 1873, I secured a large number of specimens, and verified the
structure of the nest by a careful examination of thirty-eight
examples. The nest is invariably branched and furnished with a lower
door, but the branch is of variable length, usually short, and never,
as far as I could detect, quite reaches the surface. In some cases
this branch was so short that it could scarcely contain the spider,
and, under these circumstances, it is not easy to conceive any other
use for it than that of retaining the lower door when not in use. It
may, however, enable the spider to take up a rather better position
when engaged, as she frequently is if disturbed, in keeping the main
tube closed by pressing the lower door upwards with her feet, for
then her head points downwards, and her abdomen rests in the branch.
[Illustration: _Plate XVIII._]
I have seen her in this attitude on several occasions when I had cut
out a block of earth similar to that figured in the plate. The lower
door is quite unlike that of either of the other two double-door
wafer nests, being wedge-shaped, tapering from below upwards to
the hinge, which is always placed at the point of bifurcation of
the tubes, and having two crowns separated from each other by the
gusset-like web of silk which connects the door on either side with
the lining of the main tube, one of these crowns fitting into and
closing the main tube, while the other fits into the aperture of the
branch.
The wedge-shaped structure of the door is seen in its most
exaggerated form in the nests of the younger spiders (figs. B,
B 1, Plate XVIII.), and becomes less so in the older and larger
ones (figs. A 1, A 2). I have even seen some of these lower doors,
evidently made by old spiders, which were so much flattened as to
bear a considerable resemblance to that of _N. Eleanora_.
The main tube of the nest is from 10 to 12 inches long, and usually
enters the earth almost horizontally, bending downwards from the
point at which the branch joins it, and where the lower door is
hung. This causes the lower door to lie nearly horizontally when not
in use, and its lower crown probably serves, by fitting into the
aperture of the branch, to sustain it in this position and prevent it
from falling forward. The point of bifurcation is placed, as a rule,
much nearer to the entrance of the nest, than it is in the two other
branched nests, and occurs usually within two inches of the surface
of the earth; so close is it indeed that, on lifting the upper door
and looking in, one may frequently see the lower door move across
and close the passage down the main tube, pushed by the spider from
below. This frequently enabled me to secure the spider without having
to follow her to the bottom of the nest; and, when fortune favoured
me, I secured a block of earth by one rapid sweep of the knife (a
common table-knife), which furnished me at once with a good specimen
of the nest and of its occupant.
When the spider has once fairly determined upon resistance, it is
scarcely possible to make her retreat without destroying the nest,
and, in one case, when I tried to push the lower door down from
above, while she was pressing it upwards from below, I found that,
without crushing my opponent, I could not succeed.
There were probably young in the nest on this occasion, for I have
frequently found them in the nests with the mother at this season. In
no case did I even catch a glimpse of the male, and this sex is at
present unknown.
The young spiders make their nests at an early age, and there can
be no doubt that _N. congener_ enlarges its dwelling from time to
time as growth demands, just as the trap-door spiders at Mentone
do. Indeed in one of these new Hyères nests I found, outside the
main tube and some way above the existing lower door, a former
and disused lower door much smaller than the one then in use, and
which had evidently belonged to the nest at a previous stage of its
development. I have observed this before in the nests both of _N.
Manderstjernæ_ and _N. Eleanora_.
This new type is strictly intermediate between the double-door
unbranched wafer nest constructed by _N. Eleanora_, and the
double-door branched wafer with the descending cavity which I am now
about to describe.
This latter nest, the work of _N. Manderstjernæ_, Auss.[143]
(formerly called _N. meridionalis_), has already been partially
made known by the figures and description given of it in _Ants and
Spiders_ (Plates IX., X., and XI., pp. 98, 100, and 104); but I have
to confess, with great regret, that when these illustrations and
descriptions were published, I was not fully acquainted with the true
structure of this nest, having overlooked the existence of a short
descending cavity which leaves the main tube a little above and on
the opposite side to the ascending branch. This cavity is always
present, but the very largest and oldest spiders usually allow it to
become filled up with remains of food and particles of earth, and
sometimes even spin silk across its entrance, in which case it can
only be traced on very close examination.
[Footnote 143: This spider was described by Mr. Pickard-Cambridge at
p. 101 in _Ants and Spiders_, under the name of _N. meridionalis_,
Costa. This name has now to be abandoned for reasons given in full
by Mr. Cambridge at p. 283, below. It would appear that a spider
discovered by M. Simon in Corsica corresponds more closely with the
_N. meridionalis_ of Costa than our spider of the Riviera does.
Moreover, since _Ants and Spiders_ was written I have had the good
fortune to obtain at Mentone four male examples of our supposed
_meridionalis_, and these prove to possess the same characters as
those assigned by Prof. Ausserer to a male spider which was captured
at Nice, and named by him _N. Manderstjernæ_. This specimen is now
in the possession of Dr. L. Koch, to whom I am much indebted for
having kindly entrusted it to me for examination. This enabled Mr.
Pickard-Cambridge to assure himself of the specific identity of his
_N. meridionalis_ with _N. Manderstjernæ_, which latter name it must
for the future bear.]
It was from an old nest such as this, in which the descending cavity
had been closed up, that the large drawing at fig. A on Plate IX.
of _Ants and Spiders_ was made, and this figure, therefore, still
remains substantially correct.
But in the case of the other illustrations--namely, fig. B, Plate
IX., fig. A, Plate X., and figs. B and B 1, Plate XI., where nests of
young spiders, or of spiders which, though adult, have not attained
the maximum size, are represented, this descending cavity, though
overlooked by me, should have been shown, for it must certainly have
existed.
Its presence was first observed by the Honourable L. G. Dillon, who
detected it when tracing the course of the main tube upwards from
below. I had always followed the tube from above downwards, and in
so doing must have unwittingly filled up the descending cavity (the
existence of which I was far from suspecting) with detached particles
of earth.
I will own that, when Mr. Dillon first showed me this new feature, I
hoped that it might prove to be something accidental and exceptional;
and it was only after careful examination of a large series of nests
of all sizes, that I gradually and almost unwillingly admitted that
this descending cavity formed an important feature in the typical
structure of the nests.
I now see, however, that the presence of this cavity adds
considerably to the interest of the structure as a whole, and places
its architect quite at the head of all the builders of trap-door
nests. This type should now be called, for the sake of distinction,
the _double-door, branched, cavity, wafer_ nest, to avoid confusion
with the _Hyères branched nest_.
I am now about to endeavour to atone for my past oversight by giving
new illustrations (Plate XIX., figs. A and B) and descriptions of
this very remarkable nest; while I would at the same time beg the
indulgence of my readers for past and present shortcomings, reminding
them that the interest which attaches to structures of this kind is
proportioned to the complexity and subtlety of their contrivance,
and, therefore, to the difficulty we experience in properly
understanding and describing them.
[Illustration: _Plate XIX._]
It will be seen by a reference to Plate XIX.,[144] figs. A and A 1,
that in addition to the cylindrical branch, which mounts upwards,
there is a shorter branch which leaves the main tube on the opposite
side (on the left as seen in the Plate), and takes a downward course.
Now this descending branch, which is barely more than an inch in
length, is a cavity of variable form, being sometimes cylindrical,
and sometimes egg- or even watch-shaped,[145] but there is one
particular in which it never varies, and that is the position of its
elliptic orifice. This orifice is always situated on the opposite
side of the main tube to that on which the ascending branch leaves
this latter, so that the whole nest, when seen in section, presents
the figure of a St. Andrew's cross, only with arms of unequal length.
[Footnote 144: A nest of a scarcely half-grown spider is here
represented in order that sufficient space might be gained to show
the lower door in its two positions. The perfect cavity is still
found in nests of much larger dimensions, and occasionally, indeed,
in nests of almost the maximum size.]
[Footnote 145: I take the liberty of coining a word to replace
"lenticular," the form of a watch being more familiar than that of a
lens.]
But the most remarkable point is that, when the lower door is pushed
across so as to close the main tube (as shown in fig. A, Plate XIX.),
it will invariably be found to lie in such a position that its
lower extremity exactly meets the lower lip of the orifice of the
descending cavity, when it will be seen that the semi-cylindrical
surface of the lower door then coincides with, and appears to
continue and form part of, the lower wall of the descending cavity
on the one side, and of the corresponding wall of the main tube on
the other. When the upper portion of the main tube is thus united
to the cavity the two combine to form what appears like a short,
independent unbranched nest.
Now, if we fancy ourselves an insect entering the nest in search
either of the spider, her eggs, or young, I think it is plain that,
when the lower door is in this position (fig. A), we should probably
walk straight down to the bottom of the cavity, expecting to find our
prey there, and should then return by the way we came, impressed with
the belief that we had explored the whole nest, the secret of the
lower door remaining undiscovered.
Whether this imaginary case may, or may not, represent what really
takes place, is of course mere conjecture; but the constant
occurrence of this beautiful adaptation of the various parts to
one another, surely points to the conclusion that this is no mere
coincidence, but rather a subtle contrivance having some very
definite use and meaning.
We must admit, however, that it is difficult to conceive why, if this
structure is of such great utility, it should be abandoned by the
oldest and largest spiders.
Among the possible answers to this question I think that one of
the more probable is that this arrangement may have been specially
devised for protection against some enemy which the aged spiders have
ceased to fear.
Indeed it is not unlikely that these aged spiders may have come to a
time of life when they no longer lay eggs, and so do not need to keep
up all the defences which they employed when they had families to
protect.
Since my attention was drawn to the existence of this cavity in the
dwellings of _N. Manderstjernæ_ I have never noted the presence of
young in those nests in which the cavity was filled up and disused;
but then I have only exact records with reference to this point in
the case of seven nests.
In these seven nests, however, there was no free cavity, and there
were no young spiders, though it was at the season when it was common
to find young in the nests.
The question, therefore, remains open, and further observations
on this head would be very acceptable. I detected the _débris_ of
insects, and especially the horny coats of ants, in the descending
cavity, in many nests; and in some of the oldest, where it had become
completely blocked up, these remains still indicated its former
outlines and position.
The nests of _N. Manderstjernæ_ at Cannes correspond both in respect
of the cavity and of their other characteristics with those at
Mentone. _N. Manderstjernæ_ occurs pretty abundantly at San Remo in
the olive-grounds east of the Sanctuary, but I can say nothing as
to whether the nests there possessed the cavity or not, for, when
I was there, I was not aware of its existence. I obtained a single
example of _N. Manderstjernæ_ and its nest at Hyères, and this is the
westernmost point at which this species has as yet been detected.
We have now passed in review all the seven known types of true
trap-door nest, and have taken note also of the lower and more
rudimentary forms of nest, such as that of _Atypus_, and the funnel
nest of _Cyrtauchenius elongatus_, neither of which is furnished with
a door.
Among the true trap-door nests, those of the cork type stand in a
measure alone, being distinguished from all the others by their solid
surface doors, composed of many layers of silk and earth; and we do
not at present know of any intermediate forms linking the cork and
wafer types together. But among the various nests which represent the
wafer type the case is different, for here the types naturally fall
into a progressive series, such as that represented in the diagrams
(Pl. XIV., p. 193).
If we try to picture to ourselves the stages through which the most
complicated wafer nest--namely, that of the _double-door, branched,
cavity_ type (Diagram G 1) may have passed in the course of its
development from a simpler ancestral form, we should _à priori_
expect to find precisely such structures as the _Hyères double-door
branched_ nest (Diagram F), and the _single-door branched_ nest
(Diagram D) forming successive halting-places in the advance from the
primitive _single-door, unbranched_ nest (Diagram C).
The _double-door unbranched_ type may in like manner find its
prototype in the same original single-door unbranched nest (C), which
we may look upon as the parent idea, from which all these structures
have been derived.
Bearing this in mind, and remembering that kinship between living
creatures is not only revealed to us by likeness in structure and
colour, but also by similarity in habits and instincts, it becomes
of interest to trace any resemblance that may exist between these
wafer-nests and the dwellings constructed by _Lycosa narbonensis_,
a species belonging to the allied family of _Lycosidæ_, and which
closely resembles the true _tarantula_[146] of Southern Italy.
[Footnote 146: In the United States, and indeed in the New World
generally, it seems to be the custom to call all the larger "ground
spiders," and especially the trap-door spiders, Tarantulas, but
these, in fact, form a distinct group by themselves, belonging to the
family _Lycosidæ_.]
I first made the acquaintance of _Lycosa narbonensis_ near the
glass-works west of Cannes, where this spider may not rarely be found
living in tubular burrows in sandy clearings among the pine woods
along the shore (_Pinus pinea_, the stone pine).
I have already (_Ants and Spiders_, p. 146), alluded to an account
given by M. Léon Dufour of his observations on the nest and habits of
the true tarantula (_Lycosa tarentula_), which he discovered in Spain.
The nests of _L. narbonensis_ at Cannes resembled those described by
M. Dufour, but the cylindrical, subterranean burrows were apparently
shorter. It was extremely difficult to trace their course, on account
of the loose sand which poured into the tubes and choked them up, and
I only succeeded in doing so completely in one case, when I stuffed
the tube with cotton-wool before proceeding to dig. Here the open
tube, which was quite simple, and about 1 inch in diameter, descended
vertically for 3-1/4 inches, and was then suddenly bent so as to
become horizontal, terminating shortly afterwards in a triangular
chamber, the floor of which measured 2 inches across at the widest
part, and was strewed with the remains of beetles and other insects.
The nest was lined throughout with coarse silk, which had a blackish
hue, owing to the presence of the filaments of what I believe to have
been some undeveloped fungoid growth. The mouth of the tube was open,
and frequently surmounted by a short tubular prolongation, commencing
at the surface of the ground, which formed a sort of chimney about an
inch high and from an inch to an inch and a quarter across; this was
composed of fibres of plants, pine-needles, and especially of a large
branching lichen, very common in the neighbourhood of the nests, and
all these materials were woven together and kept in place by a few
threads of silk spun here and there.
It was not every nest that was furnished with a chimney, nor were
all the chimneys equally complete, for in some cases they consisted
merely of a small rim or one-sided lip, while in others they
resembled little birds' nests, and were sufficiently firm and compact
to permit of my carrying them away. It appeared to me that these
chimneys served as screens to prevent the loose sand from being swept
into the burrows by the winds which rage over that open seashore
plain, and that they were more or less complete in proportion as
the exposure was greater or less, and the sand looser or more bound
together.
I captured eight of these spiders, and here, as in the trap-door
group, the female alone inhabited the nest.
Besides this habit, they have other points in common with trap-door
spiders; such, for example, as the resemblance which exists between
this nest and that of _Theraphosa Blondii_ from Brazil (see p. 188,
above), and between the chimney of this Tarantula and the aërial
prolongation of the tube sometimes found in nests of the wafer type.
But perhaps the most suggestive point of resemblance consists in
the habit which this Tarantula possesses of covering and closing
the aperture of the nest during the winter with a thin layer of
materials, similar to those of which the chimney is composed,
and, like them, bound together with silk. This is, in fact, an
immovable wafer-door, and precisely resembles those which I have
seen constructed by _Nemesia Manderstjernæ_, and _N. Eleanora_, when
captive and placed in an artificial hole in the earth.
The tubes are, as has been already stated, open during the spring,
and we may suppose that the spider, on the approach of warm weather,
wakes up from her winter lethargy, and tears away this concealing
thatch. But if one of these spiders should by chance happen to free
this silk-woven thatch by cutting round some three-fourths of its
circumference, so as to leave it still attached to the rim of the
aperture of the nest by the remaining quarter, she would then have
made for herself a veritable, though rather rude trap-door of the
wafer kind.
It is most likely, however, that the spider knows what she is about
and that a door to her dwelling would be the reverse of an advantage
to her, for she is more powerful and swifter than the generality of
European trap-door spiders, and, as she probably lives by leaping out
upon and hunting her prey, she no doubt needs to have the entrance to
her nest free of all encumbrance.
I am indebted to the Rev. W. G. Brackenridge for evidence of the very
interesting fact that _Lycosa narbonensis_ closes her nest at Cannes
in the winter.
I was aware that Latreille stated that the Tarantula possessed this
habit,[147] and I was anxious to know whether the species which I had
detected at Cannes, inhabiting as it did open nests in the month of
May, would also exhibit this curious custom. Being unable to visit
Cannes myself during the winter, I applied to Mr. Brackenridge,
who, on the 28th of January last (1874), secured a very perfect
specimen of the aërial portion or chimney of one of the nests having
the orifice closed in the way above described, and most kindly
transmitted it to me.
[Footnote 147: P. A. Latreille, Mem. Soc. Hist. Nat., Paris (an. VII.
de la République), p. 124: "L'araignée _tarentule_ ferme aussi son
habitation, mais cet opercule n'est pas mobile, et n'est construit
que pour l'hiver."]
I have, on a very few occasions, found the doors of a wafer or cork
nest spun up during the winter at Mentone, and on digging have
discovered the spider alive, though partially torpid, inside; but
this is quite an exceptional event. I should much like to know,
however, whether this becomes the rule in the case of the nests of
those trap-door spiders which inhabit climates less favoured than
that of Mentone.
In my concluding remarks in _Ants and Spiders_ I called attention to
the importance which attaches to a knowledge of the food and manner
of feeding of any creature whose life-history we may wish to study,
and I would now once more press the subject on the attention of my
readers. For the range and distribution of a species largely depends
upon the nature of its food, and this will also be an indication
of the rivals with which it has to compete in the struggle for
existence; the times and seasons of its activity, and in many cases
even the structure and position of its dwelling-place will be
governed by this same all-important question of food-supply.
I have now detected the remains of insects, and of ants especially,
in the nest of every species of trap-door spider which I have
examined _in situ_; very frequently, however, one may open several
nests in succession without finding any of these _débris_, and at
other times they will only be detected beneath the existing bottom of
the tube, layers of silk having been spun over successive layers of
refuse.
The horny coats of ants form by very far the largest proportion of
these remains, and I have lately been much struck by the number of
instances in which, while digging out ants' nests at Mentone, I
have found trap-door nests (especially those of _N. Manderstjernæ_
and _N. Moggridgii_) in their midst, the tubes often traversing the
very heart of the ants' colony and coming into close contact with
the galleries and chambers of the ants. The doors in these instances
had almost always escaped my notice, and, indeed, they so closely
resembled the surface of the ground that even when I knew, from
having accidentally cut across the tube below ground, that one of
these doors must lie near a given spot, yet I could only discover it
by following the passage from below upwards. This perfect concealment
is doubtless of essential importance to the spiders' success in life,
for, if they once alarmed the whole colony of ants and let them know
the exact whereabouts of their lurking-place, they would soon learn
to avoid it.
But, as it is, the work of opening the door, snatching in an ant, and
closing it again, is but the affair of a second or two, and before
the companions of the victim have time to realize the nature of the
phenomenon, the gaping earth has closed again and become once more,
to all appearance, part of the solid and trustworthy ground.
I have seen _N. Manderstjernæ_ snatch at insects in this way during
the daytime, and I well remember how I started on one occasion when,
as I was looking fixedly at a small blue gnat which I had taken for a
moth, I saw the earth suddenly open and one of these spiders partly
emerge, make a swift stroke at the insect, and withdraw again as
swiftly.