606 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
encased in thick plates of enamel, and the jaws are remarkably strong and powerful, 
and armed with numerous teeth; the body is covered with minute scales, pointed 
at the free extremity, and reminding one forcibly of the shagreen of a selachian. 
The body, including the head, is 6°5 inches in length ; the head occupies one-third 
of this length, and 1-5 inch must be added for the tail, to give a total length of 
8 inches. Its height, in front of the dorsal fin, is 2 inches; the height diminishes 
to the base of the caudal fin, which is 0-4 inch. The whole of the body is well 
preserved. The pectoral and ventral fins are unfortunately in a rather frag- 
mentary condition. 
The head is slightly less in height than its length; the supra-occipital area is 
large and prominent, with a well-rounded margin. The distance between the 
orbits is large, and is occupied by a strong external osseous plate. The 
orbit is round and small, 0°6 inch from the snout and 1°5 inch in front of the 
posterior margin of the operculum. Of the opercular apparatus the pre-operculum 
occupies the largest space; it is 1°5 inch in height and half that in breadth, sub- 
angular at the top, with anterior concave margin and convex posterior one; the 
lower portion curved forwards towards the jaws. The operculum is a long and 
narrow bone extending parallel with the pre-operculum, but expanding somewhat 
in breadth towards its lower extremity ; its free posterior margin is more or less 
sinuous. An inter-operculum extends at the base of the pre-operculum ; it is a small 
bone: the sub-operculum was probably present, but is not well preserved. The 
lower jaw is strong, 1:4 inch in length, broadest at the back, and tapering towards 
the snout. The alveolar surface is straight, and provided with numerous small, 
closely-set, slightly curved, sharply-pointed teeth. The upper jaw is provided 
with a similar dental arrangement. The exposed surface of the bones of the head 
is smooth; the under surface, where exposed, is covered with minute pittings, 
sometimes without any apparent arrangement, at others, as in the opercular bones, 
exhibiting a series of lines of pittings radiating towards the free margin of 
the bone. 
The spinal column is composed of thirty vertebrae, of which eleven are caudal ; 
they are large; anteriorly the height is equal to the length, but towards the 
caudal extremity the height diminishes. The ribs are numerous, fine, and 
tolerably long. The neural spines are comparatively short and strong. A series 
of sixteen interneural spines support the dorsal fin. The hzmal spines are similar 
to the neural, but are curved backwards. A series of interhemal spines, short 
and weak, support the anal fin. 
The dorsal fin is situated midway between the snout and the base of the tail; 
it comprises fourteen rays, the anterior one 1:0 inch in length; the succeeding 
rays gradually diminish in length, and the fin, when expanded, as in the specimen, 
has a triangular form, the base slightly longer than the two sides; the rays of the 
fin are strong, and divide only towards the extremity. 
