The mandibular tooth, which is shown in Pl. 2, fig. 3, is preserved on
the right side only. Its dimensions are as follows: Length anteriorly in
a straight line, 75 mm.; length from the apex to the posterior end of the
root, straight, 60; greatest antero-posterior breadth, 28; transverse
thickness, 10; height of apex above internal superior margin of jaw when
tooth is in situ,[13] 22; antero-posterior length of base of exposed
portion, 30; distance from anterior end to posterior end of root, 37;
greatest height of the exposed dentine crown, above the cement, 14;
length of the base of the dentine crown, 12.
This tooth, as already stated, is only two-thirds as broad and
three-fourths as long as that of Sowerby’s Brodie House specimen (the
type of the species), which was an adult male, and leads to the belief
that the Nantucket specimen was a female. This is in a manner confirmed
by the Rugsund specimen, which was an adult male and had teeth as large
as Sowerby’s specimen. It has to be remarked, however, that in the
Overstrand, England, specimen (1892), which was an adult female, the
teeth did not project beyond the gums. Messrs. Southwell and Harmer say
regarding it:
The jaws were apparently completely edentulous, and although it was
possible to feel through the gums a slight prominence on either side in
the position of the teeth of the male, we could not by this means
definitely satisfy ourselves with respect to this point, nor were we
able to ascertain the presence of any other rudimentary teeth in either
jaw. The evidence which exists on this subject is favourable to the
view that the female of this species is not provided with any teeth
which are large enough to pierce the gums.[14]
It is probable that the teeth in the Nantucket specimen, though quite
large, did not project beyond the gums any considerable distance. The
external border of the alveolar groove behind the tooth is only 20 mm.
below the apex of the tooth, and it is not unlikely that the gums in a
specimen of this size had nearly that thickness, so that only the tip of
the tooth would project beyond them. Though the apex is acute, it has a
flat abraded surface anteriorly, which, however, is but 4 mm. long. It
seems probable, on the whole, that the teeth in the female may be quite
large without projecting more than a few millimeters beyond the gums.
In shape the tooth of the Nantucket specimen is almost identical with
that of Sowerby’s Brodie House adult male, as figured by Lankester. The
dentine at the apex is more nearly white than the cement which surrounds
it. The superior margin of the latter is not a plain ring, but sends
upward a papilliform projection on each side. The dentine itself has two
vertical grooves on each side. The root of the tooth ends very obliquely
and is rugose and irregular. The cavity is closed.
Grieg remarks as follows regarding the structure of the teeth of the
Rugsund specimen:
Sections and microscopic preparations of the alveolar tooth of this
whale show that its apex consists of dentine, within which is found an
inner pulp cavity 4 mm. long and 1 mm. broad. The dentine, the
structure of which agrees with that which Turner found in _Mesoplodon
bidens_ and _Mesoplodon layardi_, is yellowish white, with the
exception of the part nearest the pulp cavity, which is yellowish
brown. It seems to correspond most closely to what Ray Lankester called
osteodentine. Throughout the tooth the dentine is covered with a very
thin layer of shining white enamel. The enamel is, however, lacking on
the front of the tooth, having probably been worn away. A section
through the middle of the tooth, at right angles with the V-shaped
furrow, shows a yellowish cement layer from 3 to 5 mm. broad, which is,
however, worn away on the front of the tooth. Within the cement layer
is a white, amorphous, calcareous mass, forming a band from 1.5 to 3.5
mm. broad, which appears to correspond to Ray Lankester’s “globular
matter” and Turner’s “modified vasodentine.” The mass seems to agree
most closely with Ray Lankester’s “globular matter,” as it has “no
structure excepting an indistinct botryoidal character visible with a
low magnifying power.” The core of the tooth consists of dentine, the
inner layer of which is brownish, while the outer is rather whitish
yellow. As above mentioned, the dentine is visible on the front of the
tooth, since both the cement and the amorphous, calcareous mass are
worn away. Moreover, it is clear that on the front of the tooth the
dentine is not covered by enamel. The pulp cavity is reduced to a fine
pore. A section across the root of the tooth shows an outer yellowish
cement layer, from 2 to 5 mm. broad, while the interior of the tooth is
filled with a white, amorphous, calcareous mass, which is interspersed
with thin yellowish lamellæ of dentine. Here and there, also, thin
lamellæ are seen to extend from the outer cement layer into the white,
amorphous, calcareous mass. The dentine lamellæ appear to be identical
with what Ray Lankester calls osteodentine. No pulp cavity is visible
in the root of the tooth.[15]
The dimensions of the Nantucket skull are given in the following table in
comparison with those of seven European skulls of _M. bidens_. Dimensions
of the Annisquam, Massachusetts, skull are also added for purposes of
comparison, although it represents another species (see p. 9).
_Dimensions of eight skulls of Mesoplodon bidens and one skull of M.
densirostris (?)._
Column headings:
_M. bidens._
B: Nantucket, Massachusetts, 1867, M.C.Z., female? adult.[a]
C: Scotland, 1872, Turner, female young.?
D: Fæø, Norway, 1895, Grieg, female? young.
E: Shetland, 1881, Turner, male adult.
F: Rugsund, Norway, 1901, Grieg, male adult.
G: Udsire, Norway, 1869, Malm, male (No. 1).
H: Vanholmen, Sweden, 1881, Malm, male (No. 2).
I: Landenæs, Norway, 1895, Grieg, male.
_M. densirostris. (?)_
J: Annisquam, Massachusetts, 1898, True, female young.
Measurements. B C D E F G H I J
mm. mm. mm. mm. mm. mm. mm. mm. mm.
Total length [b]765+ 749 620 743± ... 733 740 660 [c]622
Length of rostrum [b]483+ 489 400 ... ... 485 500 410 [c]377
Tip of beak to [bd]607+ 572 ... ... ... 582 590 517 [cd]466
end of
pterygoid
Height from 277 241 ... 254 267 272 258 235 248
vertex to
pterygoid
Breadth between [e]277 286 [f]254 267 292 293 253 [f]260 [278]
orbits
Breadth between 289 292 262 292 295 298 270 268 266
zygomatic
processes
Breadth at 184 197 170 184 193 187 170 175 [166]
maxillary
notches
Breadth of beak 42 51 38 ... ... 36 46 [g]40 38
at middle
Depth of beak at 35 ... [h]31 ... ... ... ... [h]33 51
middle
Greatest breadth 131 127 115 114 116 129 124 122 ...
of premaxillæ
proximally
Greatest breadth 107 102 [h]104 102 108 108 100 [h]76 92
of premaxillæ
in front of
anterior nares
Greatest breadth 54 ... 53 ... 53 50 50 50 39
of anterior
nares
Length of 90 ... ... ... ... ... [h]66 82
temporal fossæ
Breadth between 222 ... ... ... ... ... ... ... 208
temporal fossæ
Breadth of 50 ... ... ... 49 56 54 80 46
foramen magnum
Length of [c]651 [ij]470 543 [i]464 ... 639 640 560 ...
mandible
Length of 237 241 162 ... ... 212 220 160 ...
symphysis
Greatest depth 106 114 92 102 116 110 97 95 ...
of mandible
[a] The size of the teeth makes it quite certain that it is an adult
female.
[b] End of beak broken off about 30 mm. from tip.
[c] Right side. Add 31 mm. for breakage.
[d] In median line.
[e] At middle.
[f] Between “suprafrontal processes of max.”
[g] Grieg’s fig., p. 18, shows 44 mm.
[h] From Grieg’s fig., p. 18.
[i] “Length of ramus.” Length of mandible=699 mm.
[j] In Trans. Roy. Soc. Edinburgh, vol. 26, 1872, p. 776.
MESOPLODON DENSIROSTRIS (Blainville)?
_Delphinus densirostris_ Blainville, Nouv. Dict. Hist. Nat., 2d ed.,
vol. 9, 1817, p. 178.
_Ziphius seychellensis_ Gray, Zoöl. _Erebus and Terror_, 1846, p. 28.
The skull of the specimen from Annisquam, Mass., (Pl. 1, fig. 2) is, I
regret to say, in rather poor condition. It is broken in the left orbital
region, and all the bones, especially those of the beak, are warped by
weathering. The proximal extremity of the left premaxilla is lacking and
also the tip of the beak.
The skull is obviously that of a young animal, as all the sutures are
open and the surface of the occipital condyles is pitted, owing to
imperfect ossification.
Although the dimensions of the skull, with a few exceptions, agree well
with those of young specimens of _M. bidens_, as shown by the foregoing
table (p. 8), certain differences stand out conspicuously. The most
salient of these is the depth of the beak as a whole and the depth and
shape of the rostral portion of the premaxillæ. The latter portion of the
premaxillæ instead of being low, with a straight inferior margin, is very
high, with the inferior margin strongly convex. At the middle of the beak
the premaxillæ are higher than the maxillæ on which they rest. It is true
that the shape of the beak varies greatly with age in _bidens_ and other
species of _Mesoplodon_, but I do not find any evidence that such a
change as is here indicated takes place in _bidens_. The form of the beak
and of the rostral portion of the premaxillæ is that of _M.
densirostris_.
The beak is almost as broad at the base as in _bidens_, but the lateral
free margin of the maxilla anterior to the anteorbital notch instead of
continuing along the side of the beak nearly to the tip, as in _bidens_,
ends at a point about 90 mm. in front of the line of the notch, beyond
which the sides of the beak are vertical.
The margin of the maxilla immediately anterior to the anteorbital notch
is a little damaged, but there was apparently no strong tubercle at this
point, and the surface of the maxilla, though convex, is not raised into
a distinct ridge. In a young skull, however, one would not expect to find
a high ridge. The palatines are visible from above, which is not the case
in _bidens_.
The maxillary foramen is situated a little in advance of the premaxillary
foramen and is directed forward, and, as Dr. Glover M. Allen has pointed
out, connects with a broad groove which runs forward along the
triangular, horizontal portion of the maxilla at the base of the beak.
The maxillæ are much broader behind the notch than in _bidens_, and the
anterior end of the malar forms the bottom of the notch. The premaxillæ
are noticeably constricted immediately in front of the premaxillary
foramina, and the expanded portion just behind these foramina is nearly
horizontal, with a low transverse ridge near the middle. The proximal end
of the premaxillæ is nearly vertical. The anterior nares are noticeably
small. The foramen magnum is large, with a trifoliate outline (Pl. 10,
fig. 2). The palate at the proximal end presents a median ridge with a
narrow groove on each side. The palatines extend as a broad band much
beyond the pterygoids anteriorly. The vomer is visible below for a space
of 142 mm. near the end of the beak. A very small piece is also visible
at the base of the beak, between the palatines and pterygoids. The
inferior surface of the pterygoids is convex on the side adjoining the
lateral free margin (Pl. 4, fig. 2).
This skull is peculiar in that there is no very distinct basirostral
groove and that the basirostral ridge, as already stated, extends forward
only about 90 mm. Below this ridge is a shallow broad groove which
narrows rapidly forward and can be traced to the extremity of the beak,
where it broadens out somewhat (Pl. 7, fig. 2).
While this skull agrees in size and in many of its proportions with
similar skulls of _M. bidens_, it differs from that species and agrees
with _M. densirostris_ in the breadth across the anteorbital region, in
the depth of the beak and its shape at the base, in the shape of the
premaxillæ both distally and proximally, in the direction of the
maxillary foramen, and the shape of the maxillary bone in front of the
same, in the occupation of the base of the maxillary notch by the
anterior end of the malar, in the absence of any distinct maxillary ridge
above the notch, in the forward extension of the palatines, and in the
shape of the foramen magnum.
Flower states that there is a deep basirostral groove in _M.
densirostris_,[16] but neither the figure in Gervais’ Zoologie et
Paleontologie Française,[17] nor that in Van Beneden and Gervais’
Ostéographie des Cétacés,[18] shows such a groove. The conformation of
the base of the rostrum appears to be about the same as in the Annisquam
skull.
In regard to differences between this skull and those of _M.
densirostris_ it should be stated that in the latter the premaxillary
foramina are situated farther apart, and that the maxillary foramina are
situated considerably in advance of those of the premaxillæ instead of
nearly in line with them.
The Annisquam skull approaches _M. europæus_ in several characters, but
these are such as _europæus_ shares with _densirostris_. The principal
ones are the breadth of the maxillæ in front of the orbits, the presence
of the malar in the base of the anteorbital notch, and the convexity of a
part of the inferior surface of the pterygoids.
Dr. Glover M. Allen has given an account of the exterior, skeleton, and
teeth of this specimen, from which the following particulars are
extracted:[19]
Regarding the Annisquam specimen no color notes were taken, but from a
few small photographs in the possession of the Boston Society of
Natural History, it appears evident that the ventral portion was of a
lighter tint, and in one of the views a few oval whitish spots are seen
on the side a trifle behind the middle portion of the body. Another
view shows the convexity of the posterior margin of the flukes at the
median point, as well as the prominent dorsal fin. The lower jaw
protruded slightly beyond the upper. Measurements of this specimen, as
noted by Professor Hyatt, are as follows: Total length, 12 feet 2
inches; from anus to bight of flukes, 3 feet 4 to 6 inches; across
flukes, 3 feet 1 inch; from tip of rostrum to angle of mouth, 1 foot 1½
inches. The gular furrows were noted as about 10 inches long and from ¼
to ½ an inch deep.
The teeth of the Annisquam specimen barely projected above the alveoli
of the jaws and are sharply mucronate. The basal portion of each,
however, is more like that of the male’s tooth [_M. europæus_] in the
slightly convex posterior outline and the forward extension of the
anterior angle. * * *
The Annisquam skeleton has 45 vertebræ. Four of the seven cervicals are
fused. The atlas, axis, and third cervical are firmly anchylosed
throughout, save for the lateral foramina for the passage of the
cervical nerves. The fourth cervical is fused to the third by the
dorsal spine on the left side and by the tip of the upper lateral
process of the same side. Its centrum, right half of the dorsal spine
(the spine is divided medially), and the remaining lateral processes
are free. * * * The epiphyses of the fourth and fifth cervical vertebræ
and the anterior epiphysis of the sixth cervical are fused to their
respective centra, but all the other epiphyses of the vertebral column
and of the pectoral limbs are free.
The Annisquam skeleton has nine dorsal vertebræ with their
corresponding pairs of ribs. * * * The sternum of this specimen
presents few points of interest. It consists of four pieces, the
anterior-most of which is largest, slightly hollowed above, and
correspondingly convex below. The three remaining pieces are nearly
flat, with a deep median notch at the anterior and posterior border of
each. The posterior piece evidently represents a fusion of the elements
of two segments, as there are articular surfaces for two pairs of ribs.
From the foregoing, it appears that the Annisquam specimen probably had
one or two vertebræ less than _bidens_ or _europæus_, and that the
sternum was somewhat differently shaped. The tooth, which is figured by
Doctor Allen, is conical, compressed, 54 mm. long, 30 broad at the base,
and resembles teeth of immature _bidens_.
Although with such scant material it is not possible to determine
satisfactorily the identity of this third species of _Mesoplodon_ in the
North Atlantic, represented by the Annisquam specimen, I feel convinced
that that specimen does not belong to _M. bidens_ and that there is a
strong probability that it belongs to _M. densirostris_. It is true that
the latter species has been found hitherto only in the Indian Ocean and
about Australia, but we know so little about the distribution of the
ziphioid whales that, in my opinion, that circumstance by itself should
not be given very great weight.
MESOPLODON EUROPÆUS (Gervais).
_Dioplodon europæus_ Gervais, Zool. et Pal. franç., 1st ed., vol. 2,
1848-1852, p. 4; 2d ed., 1859, p. 289, pl. 40, figs. 3-6.
_Dioplodon gervaisi_ Deslongchamps, Bull. Soc. Linn. Normandie, vol.
10, 1866, p. 177.
_Neoziphius europæus_ Gray, Suppl. Cat. Seals and Whales Brit. Mus.,
1871, p. 101.
This species was based on a single specimen found floating in the English
Channel about seventy years ago. An account of the circumstances under
which it was found was given by Eugène Deslongchamps in 1866, as follows:
The head, which forms the subject of this last note, was given to my
father some twenty-five or thirty years ago by Mr. Abel Vautier, a
merchant and armorer of our town, who died at Paris two years since.
The captain of one of Mr. Vautier’s ships, on his return from a voyage
to the colonies, saw floating on the water, at the entrance to the
English Channel, the body of a large animal entirely covered by birds
(large and small gulls, etc.), which were devouring it. The ship
approached the stray, and the captain, knowing that Mr. Abel Vautier
was greatly interested in natural objects, had the head of the cetacean
cut off, fastened it securely with a cord, and let it trail behind the
ship. When he arrived at Caën he made a present of it to Mr. Vautier.
The piece had at that time an appearance anything but agreeable. Mr.
Vautier was especially fond of beautiful objects which please the eye,
and hence he offered it to my father, saying, “You, who are an
anatomist, can make better use of this than I can.” My father was
unwilling to refuse the present, but neither he nor Mr. Vautier knew as
yet of its extreme rarity. It is in fact, up to the present time, the
only specimen which exists, and is a unique object in collections.[20]
No additional specimens have been recorded from European waters or
elsewhere, and much doubt has been thrown on the validity of the species,
many zoologists regarding it as an adult of the commoner species _M.
bidens_. Van Beneden remarked in 1888:
The opinions of naturalists are divided as regards the identity of this
ziphioid, which is unique up to the present time. In the eyes of some
it represents an old male of the common _Mesoplodon_, in which the
tooth, instead of developing near the middle of the jaw, has developed
near the anterior extremity. This is the opinion of Doctor Fischer and
others, who think that this unique specimen represents merely an
individual modification and that consequently it should not figure in
the list of species. We do not share this opinion. It is not impossible
that this ziphioid may belong to the other hemisphere, and this would
explain why only one single individual has been captured in Europe.[21]
In view of the circumstances surrounding the discovery of the original
specimen, it is of great interest to find that two of the specimens from
the east coast of the United States represent the same species. As one of
them is adult and the other young, the view that the type of _M.
europæus_ is merely an old individual of _M. bidens_ is satisfactorily
disposed of, as is also the opinion that it represents a singular
individual variation.
The two American specimens which represent _europæus_ are those from
North Long Branch, New Jersey (adult female; skull, lacking rostrum and
mandible, in the Museum of Comparative Zoology), and from Atlantic City,
New Jersey (young male; skeleton, cast and photographs in the U. S.
National Museum, Cat. No. 23346).