136 
the Lower Jurassic cliffs of Cape Paterson, on the south coast of Victoria, 
are thus of special interest. I am indebted to Prof. J. W. Gregory, 
F.R.S., for the opportunity of studying these specimens. 
The tooth of Ceratodus (PI. XIV., fig. i) is firmly fixed to a recognisable 
piece of the splenial bone, and is therefore proved to belong to the left 
side of the lower jaw. It unfortunately lacks the foremost denticle, but 
clearly agrees with the majority of the Mesozoic teeth of Ceratodus in 
possessing only four denticles altogether. It is thick and robust, with the 
grinding-surface slightly convex, but wavy, and marked by a very pro¬ 
minent coarse network of ridges (fig. i). It is specially remarkable for 
the long and narrow shape of its crown, which is bounded on the inner 
side by a nearly straight margin, not angulated opposite the second or 
third denticle. So far as can be determined from a fragment, the foremost 
denticle of the tooth appears to have been relatively large, while the others 
rapidly decrease in size backwards. The second and third denticles are 
sharply compressed to an acute outer edge, and are separated by deep 
notches at the outer margin (fig. i a), though not continued as conspicuous 
ridges on the crown. Their long axes are not oblique, but directed nearly 
at right angles to the inner margin. The fourth or hindmost denticle is 
comparatively blunt. Fine horizontal lines of growth are seen on the 
flattened inner (fig. i b) and outer faces of the tooth. 
The specimen thus described differs from all the known Mesozoic teeth 
of Ceratodus in its narrowness, combined with the straightness of its inner 
margin and the direction of its second and third denticles. In these 
respects, it is interesting to observe, the tooth more nearly approaches that 
of the existing Ceratodus or Neoceratodus of Queensland (fig. 2), and its 
only striking difference from the latter consists in its having four denticles 
instead of six. The multiplication of the denticles has already been 
observed in the teeth of certain sharks as they are traced onwards in time* * * § ; 
the same phenomenon obviously occurs in Ceratodus. 
There is, therefore, no doubt that the tooth from Cape Paterson 
represents a new species, which may be named Ceratodus avus. The fossil 
proves for the first time that the remarkable Dipnoan genus to which it 
belongs had already reached the Australian region so long ago as the early 
part of the Jurassic period. At that epoch Ceratodus was still living both 
in Europe! and in North America,! while it survived in the African and 
South American regions at least until the Cretaceous period. § 
In the same rock as that from which the tooth of Ceratodus was obtained 
at Cape Paterson Mr. Ferguson found the terminal phalangeal bone shown 
in fig. 3. Among Jurassic fossils this specimen can only be compared 
with the claw of a carnivorous Dinosaur, and there is little doubt that it 
represents a genus more or less related to Megalosaurus.\\ The bone has 
decayed somewhat in the upper part of its proximal end, but is otherwise 
well preserved and displays its principal characters. The phalangeal is 
laterally compressed, so that its greatest transverse diameter is somewhat 
less than its original depth at the proximal end. The distal tapering half 
of the bone is only gentlv curved downwards, but at the same time bends 
slightly to the left side. The distal half of the lateral face is marked 
with the usual deep longitudinal groove connected with the fixing and 
* A. S. Woodward, “On the Palaeontology of the Selachian Genus Notidanus , Cuvier,” Geol. Mag. [3] 
Vol. III. (1886), p. 257. 
t Ceratodus Phillipsi, Aggassiz. “Rech.Poiss. Foss.,” Vol. III. (1838), p. 135, pi. XIX., fig. 17 ; A. S. 
Woodward, Proc. Geol. Assoc., Vol. XI. (1890), p. 292, pi. III., fig. 5. 
t Ceratodus Guentheri, O. C. Marsh, Amer. Journ. Sci. [3] Vol. XV. (1S78) p. 76, woodc. 
§ Ceratodus a f ricanus, E. Haug, “ Comptes R,endus.,” Vol. CXXXV'III. (1904), p. 1529; from Djoua, 
Timassanine, Sahara. Ceratodus Iheringi, F. Ameghino, Public. Univ. La Plata, No. 2 (1904), p. 10, fig. 1 ; 
from Patagonia. 
II It. Owen, “ Foisil Reptilia of the Wealden and Purbeck Formations,” Pt. III. (Mon. Palsoont. Soc. 
1855 [1857]), p. 19, pi. X. 
