All the species of _Crocodilus_ which I have hitherto mentioned have,
in common, the backward curvature of the premaxillo-maxillary suture to
the level of the seventh tooth. But there is a species of Crocodile,
about whose proper specific name I am by no means clear, in which this
suture passes straight across the palate, or may even be a little convex
forwards.
And not only do the skulls of this species exhibit this approximation
to those of the _Alligatoridæ_, but they resemble them still further in
their rounded snouts, their great width immediately behind the canine
groove, and in the fact that, in young specimens, one or the other
canine may be received into a pit instead of into a groove[5].
In the Hunterian Collection there are seven skulls, varying in length
from 5-1/4 inches up to 16 inches, in none of which does the crown of
the premaxillo-maxillary suture extend beyond a line joining the sixth
pair of teeth. In all there are two short ridges (convergent in young
specimens, nearly parallel in old ones) upon the lachrymal bones, which
end before reaching the anterior limits of those bones. They all have
an oblique ridge on the upper jaw above the tenth tooth; and the snout
attains the width which it has opposite this tooth immediately behind
the canine groove. In the British Museum there are five middle-sized
skulls with the same characters; but two of these have a pit on one
side of the upper jaw, and a groove on the other, and one has something
between a pit and a groove on each side.
Dr. Gray, has in his 'Catalogue[6],' mentioned the peculiar transverse
disposition of the premaxillo-maxillary suture in his _Crocodilus
bombifrons_; and on examining the two crania thus named in the British
Museum collection, one of which is 20 and the other 21 inches long, I
can discover no distinguishing character between them and those already
described. There can be no doubt then, I think, that these constant
and well-marked characters, exhibited by fourteen skulls which vary in
length from 5-1/4 to 21 inches, prove the existence of a distinct
species of Crocodile, which I would provisionally term _bombifrons_.
[5] In a skull of this species 14-1/2 inches long, in the British
Museum, the vomers are completely excluded from the palate, and
their anterior ends do not extend for an eighth of an inch beyond
the palatine part of the palato-maxillary suture, which lies on a
level with the anterior margin of the twelfth alveolus. Each vomer
is 2-3/8 inches long, and presents the same general form as that
of _Jacare_; only the anterior division is but a very small, flat
and thin plate, not a quarter of an inch long. The boundary of the
median nares is formed in equal proportions by the vomer and the
palatine, and is opposite the fourteenth tooth. The hinder end of
the vomer articulates with the end of the descending process of
the prefrontal.
[6] 'Catalogue of the Tortoises, Crocodiles, and Amphisbænians in
the Collection of the British Museum,' 1844, p. 59.
I believe that this species has been constantly confounded with
_biporcatus_, from which it may be at once distinguished by the
direction of the premaxillo-maxillary suture, and by the shape of the
snout behind the canine groove. I have found these distinctions to hold
good at all ages; but the last-mentioned difference is far more marked
in middle-aged than in either young or old specimens.
All the skulls named _Crocodilus palustris_ which I have seen are
referable either to _C. biporcatus_ or to _C. bombifrons_. With respect
to the _C. palustris_ of Lesson and Duméril and Bibron, the latter
authors consider it to be only a variety of _C. vulgaris_. Their
description would, however, apply very well to _C. bombifrons_, as I
have defined it above; and they expressly state ('Erp. Générale,' t.
iii. p. 113) that all their specimens (twelve in number and varying in
length from 30 centimetres to more than 3 metres) came from the East
Indies or the Seychelle Islands. Now, Duméril and Bibron enumerate only
three Asiatic Crocodiles--_C. biporcatus_, _C. palustris_, and _C.
galeatus_, the last of which was only known to them by description; so
that all the numerous Asiatic crocodiles which passed through their
hands belonged either to _C. biporcatus_ or _C. palustris_. On the other
hand, all the skulls of crocodiles from Asia which I have met with
(amounting to at least twenty) are either those of _C. biporcatus_ or
of the species which I have called _bombifrons_; so that I suspect the
latter title will turn out to be a synonym of _palustris_.