The fourth or great tooth below does not pierce the upper jaw
in this species.
Alligator trigonatus,( 1) ££.=82 l'Wfr*=largest.
Alligator niger, J&|=74 fHvii=largest.
In almost all, if not all of these species of Alligator from eight to
ten of the posterior teeth are straight, sub-compressed, and terminated
by an obtuse mammilloid crown.
Crocodilus rhombifer, j^ = 6 4 ’-^ la rg e st.
Orocodilus Gravesii, iKf= 6 6 ^ ^ l a r g e s t . This species exhibits,
besides the notch for the fourth lower tooth or canine, a
remarkable emargination for the elongated crowns of the ninth, tenth,
and eleventh teeth.
Crocodilus vulgaris, J|Ej|= 6 6 ixif;—largest.
Crocodilus biporcatus, i|=L*>or 19- 19= 66 or 68 | ^ 9= largest.
Crocodilus acutus, irfs 4^ ’=largest. In this species the
first ten teeth, counting from the anterior part of each side of both
jaws are pointed and slightly recurved: the rest are straight and
obtusely conical.
Crocodilus intermedius. The name of this species indicates the
gradational character between the Crocodiles and the Gavials, which
it manifests in the increase of the longitudinal over the transverse
diameter of the cranium and in the comparative slenderness of its
jaws: the alveolar border is less deeply sinuous in both jaws, and
the rami of the lower jaw are united along the anterior fourth part of
their length. The teeth are relatively smaller than in the preceding
Crocodiles ; the dental formula is i|Efs= 6 6 £|I£#largest.
The transition, of which the first steps were made by the Croco-
dili acutus and intermedius is completed by the Gavialis Schlegelii, in
which the head is more elongated and contracted, the teeth smaller
and more equal, and the anterior pair of the lower jaw received, like
the fourth pair, in notches at the outside of the intermaxillary bone,
between the first and second teeth of the upper jaw.
The first, second, third and ninth teeth of the upper jaw, are
larger than the rest, the ninth is the largest, and the superior max- 1
(1) Champsa trigonala Natterer.
illary bones are slightly expanded at the insertion of this pair of
teeth. The first, fourth, eleventh and fifteenth pairs are the largest
teeth in the lower jaw, but the anterior tusks do not perforate the
intermaxillary bones.
In the foregoing gavial-like Crocodile the narrowing of the skull
to form the jaws is gradual, but in the true Gavials the cranium suddenly
contracts into the prolonged upper jaw. In this subgenus
the two jaws together form a long, straight, narrow, and four-sided
column, with the angles rounded off, terminating in an expansion
something like that of the beak of the spoon-bill. The terminal
expansion of the upper jaw is indented by four vertical notches,
which receive the crowns of the first and second pairs of the inferior
teeth when the mouth is closed. The number of teeth is
always greater in the Gavials than in the Crocodiles or Alligators.
The formula of the common Gavial(l) (Gavialis gangeticus) is = 112.
The first five pairs of teeth above, are supported by the intermaxillary
bones ; the first, third, and fourth teeth of the upper jaw,
and the first, second, and fourth of the lower jaw are the longest.
The eight or nine posterior teeth are nearly conical, the rest are
sub-compressed antero-posteriorly and present a trenchant edge
on the right and left side, between which a few faint longitudinal
ridges traverse the basal part of the enamelled crown. (2) The
position of the opposite sharp ridges and the direction of the flattening
of the crown are thus reversed in the Gavial and in the
extinct Crocodile (Croc, cultridens), before-mentioned, which in other
respects most nearly resembles the Gavial in the form of the teeth.
In most of the extinct species of Crocodilians, the teeth are
characterized by more numerous and strongly developed longitudinal
ridges upon the enamelled crown than in the recent species, and
they are commonly longer, more slender and sharper-pointed. But in
one of the Crocodiles with sub-biconcave vertebra; (Goniopholis crassi-
dens), from the Wealden formation and Purbeck limestone, the teeth
(1) PI. 75a, fig. 3. This word ought to be written “ Gbarrial” ; but the universal adoption
of the erroneous orthography in European scientific works, and its conversion into a Latin
generic name (Gavialis\ render an alteration undesirable.
(2) Plate 75, fig; 2.
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