Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 603 
parts in which the examples at the disposal of those authors were defective. The 
average length is about 9 inches from the snout to the peduncle of the tail, the 
latter adding 2 inches. The height of the body, slightly in advance of the dorsal 
fin, is 2 inches, diminishing evenly backwards to the tail, the base of which is 
little more than 0-5 inch. The tail is widely expanded and deeply cleft. The 
dorsal and anal fins are large and powerful; the paired fins are also well 
developed. The head is large, and has the appearance, probably due to pressure 
in expanding its bony structure, of being deeper than the body. 
The head in profile is somewhat triangular; the snout obtuse, the lower 
margin, formed principally by the mandible, large and powerful, and the lower 
portion of the opercular bones extends from the snout 3 inches; the profile to 
the posterior portion of the skull 2°5 inches, and the line dividing the head 
from the body 2°5 inches. Seen from above, the head is broad, the snout obtusely 
circular. The bones covering the head are externally coated with a thick layer 
of enamel; the operculum is ornamented by radiating ridges, and other bones 
exhibit a similar character. Where the enamel has been removed and the under 
surface exposed, it is pitted in more or less parallel lines. The orbits are situated 
slightly in advance of the middle of the head, and the two are separated by only 
a small distance on the median line. The opercular bones are large, rounded, 
and extend far towards the abdominal surface. The upper jaw is composed 
of a pair of maxillaries, straight, and a considerable length; the intermaxillaries 
are short, but powerful, and are armed with long-pointed teeth ; the lower jaws 
are long and very robust; their posterior extremity is attached to a large 
quadrate bone, affording a powerful leverage. The gape is very wide; the 
dentition of the jaws is their most striking feature. A large tooth 0°7 of an inch 
in length occupies the anterior extremities of the upper jaw; it is sharply pointed, 
laterally compressed, with a sharp cutting edge extending down each side; it is 
probably anchylosed to the bone of the jaw. A number of teeth occupy both the 
upper and lower jaws; they increase in size backwards to the median portion of 
the jaws, and further back again decrease in size. The teeth are separated by 
considerable spaces in transverse section; they are a flattened oval; on each side 
a longitudinal cutting edge extends from the point downwards, as in the large 
anterior teeth. 
The spinal column consists of thirty-eight vertebra, and of these fifteen are 
abdominal and twenty-three caudal. ‘The vertebra in the anterior portion of the 
body are 0°25 inch in height and 0:2 in length; the length remains the same 
nearer the tail, but the height gradually decreases to 0°15 inch. The anterior and 
posterior surfaces of each centrum are deeply concave, and the median portion 
considerably contracted. Neural apophyses are attached to each vertebra ; the 
spines posterior to the dorsal fin curve slightly backwards and extend to the dorsal 
surface of the body; those opposite to or in front of the dorsal fin are curved 
