have crowns which are as round and as thick in proportion to their
length as in the recent Crocodiles or Alligators. Some of the teeth
of this species are even shorter and more obtuse, as are those figured
in PI. 62, A. fig. 9, a and b. The crown is traversed by longitudinal
ridges, which are more numerous, more close-set, and more neatly
defined than in the Croc, cultridens (Suchosaurus) from the same
formation. Two of the ridges, larger and sharper than the rest,
traverse opposite sides of the crown ; hut are placed as in the Gavial,
on the right and left sides, midway between the convex and concave
lines of the curve of the tooth. These ridges are confined to the
enamel; the cement-covered cylindrical base of the tooth is smooth.
The more ancient Crocodiles from the Oolite and Lias, called
Steneosawi and Teleosauri had jaws like those of the modern
Gavials, but sometimes longer and more attenuated, and armed
with more numerous, equal, and slender teeth, adapted for the
capture of fishes, which appear to have been the only other vertebrate
animals existing at those periods in numbers sufficient to
yield subsistence to carnivorous Saurians.(l)
In a specimen of Teleosaurus Chapmanni I have counted one
hundred and seventy-eight teeth, thus arranged, : the Teleosaurus
latifrons had one hundred and forty-two teeth, viz, |Eg.
The Tel. Egertoni had gif. (PL 75a, fig. 4.) Cuvier calculates
the number of teeth in the Teleosaurus of the Caen Oolite, which is
a distinct species from the two above-mentioned, to be one hundred
and eighty, viz. The enumeration will differ within small limits
in different individuals of the same species, in consequence of the
uninterrupted and irregular shedding and replacement of the teeth.
The foregoing numbers indicate those of the sockets, some of which
are almost always empty. In the Teleosaurus priscus (Crocodilus priscus,
Soemmering) the teeth appear to have been shed and renewed in a
more regular alternate order than in other species.(2)
In all the Teleosauri the teeth are more slender, less compressed
and sharper pointed than in the Gavial; they are slightly
recurved, and the enamelled crown is traversed by more numerous
(1) Buckland’s Bridgewater Treatise, i, p. 250. ’
X2) Whence the term Aelodon proposed for the species by M. H. v. Meyer.
and better defined ridges, two of which, on opposite sides of the
crown, are larger and more elevated than the rest. The fang is
smooth, cylindrical, and always excavated at the base. The teeth of
the Steneosauri, or extinct Crocodiles with long and slender jaws
and with vertebrae subconcave at both extremities, but with sub-
terminal nostrils, differ from those of the Teleosauri in being somewhat
thicker in proportion to their length, and larger in proportion
to the jaws.
A distinct genus of extinct Crocodile (Marmarosaurus) is indicated
by a form of tooth differing from that of the Steneosaurus in being subcompressed,
and in having the ridges on the basal two-thirds of the
crown shorter, more frequently interrupted, irregularly alternating,
and slightly wavy | the two opposite stronger ridges are not developed.
Teeth of this kind, with crowns fifteen lines in length, and
six lines across the long diameter of the base, occur in the Forest-
marble, PI. 75 a, fig. 5.
A more remarkable and almost heart-shaped form of tooth,
is presented by the extinct Crocodilian genus denominated, from
this character, Cardiodon. The crown of the tooth suddenly expands
above the neck, as in the Caiman, but is more flattened
transversely and is broader antero-posteriorly, terminating in an
edge before and behind, and contracting to a point above, which
is generally more or less abraded. The enamel is roughened by wavv
longitudinal ridges, with more minute rugae in their interspaces.
The fang of the tooth is smooth and cylindrical, PI. 75 a, fig. 7 .(1)
Structure. The teeth of both the existing and extinct Crocodilian
Reptiles consist of a body of compact dentine, forming a
crown covered by a coat of enamel, and a root invested by a
moderately thick layer of cement. The root slightly enlarges, or
maintains the same breadth, to its base, which is deeply excavated
by a conical pulp-cavity extending into the crown, (as indi-
(1) These teeth are likewise from the secondary rock, called Forest-marble, near Brad
ford, Writs, and I am indebted to Mr. Channing Pearce of that town, for the opportunity
of examining them. The teeth from the Wealden, supposed to belong to the H^osaurus. very
closely resemble those of Cardiodon in the superficial shape of the crown. markings, and approach them in the
U 2