538 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
the dorsal and abdominal surfaces gradually converge towards the tail; the 
peduncle of the latter is 0°3 inch in height. The anterior margin is more or 
less circular, and the general outline of the body ovoid. The tail is 1:3 inch 
in length. 
The head, rounded in outline anteriorly, is slightly convex posteriorly. The 
orbit is large and high; the opercular bones are higher than broad, but in this 
specimen are not very well preserved. The supra-orbital region is small; the 
plates enveloping the cranium, as well as others, are comparatively strong and 
are enamelled. The infra-orbital region is occupied by bony plates of considerable 
extent, and the maxillary, conterminous with the lower margin of them, is well 
developed, and extends a length of 0°8 inch. The anterior part of the upper 
jaw is imperfect. The mandible is large and strong; on its anterior extremity 
there are indications of a number of minute teeth. Branchiostegal rays are 
exposed, but not sufficiently well to ascertain their number. 
The spinal column consists of twenty-eight vertebre ; of these eighteen are 
caudal. They are strong, slightly higher than broad. The neural and hemal 
spines are strong, comparatively straight, and extend from the spinal column 
two-thirds the distance towards the surface of the body. There are eighteen 
interneural spines, to support the dorsal fin, and twelve interhzmal, to support 
the anal fin. The posterior termination of the vertebral column is slightly 
turned up. 
The dorsal fin extends from the base of the tail 1:2 inch towards the head. 
It is composed of eighteen rays, the anterior ones 0°6 inch in length, diminishing 
slightly backwards. The first two or three rays are shorter and spinous; the 
remainder bifurcate, and are articulated. The anal fin is shorter than the 
dorsal; its base is 0°8 inch in length; it has three strong, pointed rays in front ; 
the remaining nine are similar to those of the dorsal fin. The caudal fin is 
large and deeply forked; the upper lobe consists of twelve rays, and the 
lower of nine, strong and undivided at the base, but bifurcated and articulated 
towards the distal extremity. In addition there are five or six short, imbricating 
spinous rays at the base of both the upper and lower lobes. 
The pectoral fin is on the side of the body, at one-fourth the height of the 
fish above the abdominal margin. It consists of fourteen or fifteen rays, 0°6 inch 
in length; distal margin rounded. ‘The ventral fins are on the abdominal surface, 
in advance of the pectorals. Its rays are 0°7 inch in length; they are closed 
against the surface of the body, so that their number cannot be seen. 
Patches of scales extend over the surface of the body, but are not very 
well preserved; they were thin and apparently small. The plates enveloping 
the head were thicker, and in some fragments an imbricated margin is exhibited. 
This species approaches most nearly to that of Pycnosterinx heckelii, Pictet. 
It may be distinguished by its slightly more elongated form, the narrowness 
