544 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
all respects well preserved, except the ventral fins, of which only the base 
remains. 
The head is large; orbit superior and moderately large; cranial bones well 
developed; mouth small, and jaws short, but thick and strong, furnished with 
villiform teeth. Operculum large, anterior surface concave, posterior one convex. 
Preoperculum, in the form of an elongated triangle, is longer than the operculum ; 
attached to its lower extremity there is an interoperculum, extending forwards 
to the posterior extremity of the lower jaw; and a suboperculum completes the 
series, the latter is attached to the lower extremity of the operculum, its height 
equal to about half its length. A series of branchiostegal rays is present, but 
the exact number cannot be stated, a portion of them being hidden under the 
opercular apparatus. 
The vertebral column extends in a straight line; it is composed of thirty-three 
vertebrae, of which eighteen are caudal. The vertebre are, on an average, equal 
in height to their length. Neural apophyses extend from the upper surface of the 
vertebrae; they are strong, and more or less straight; to their distal extremities 
is attached a series of interneural spines, which in turn support the numerous 
rays of the dorsal fin. A similar arrangement exists on the hmal surface of the 
caudal portion of the body supporting the long anal fin. A series of ribs, short, 
strong, and nearly straight, may be distinguished in the abdominal cavity. 
Three or four vertebre at the caudal extremity turn up towards the upper lobe 
of the tail. 
The dorsal fin extends from a point 1:0 inch behind the snout to the base of 
the tail. It is stated by M. Costa to be composed of forty-five rays. In this 
specimen the number cannot easily be distinguished, but there are more than 
forty interneural rays, and each one appears to support or be attached to a ray of 
the fin; the anterior rays are strong and spinous, 0°5 of an inch in length; the 
anterior ray 1s supported by four imbricating shorter spines. The soft rays are 
divided, and decrease in length backwards. The anal fin is 0-9 of an inch in 
length. Its anterior rays are spinous, and are supported, like the dorsal, by four 
or five imbricating short rays; the soft rays of the fin diminish in length back- 
wards. ‘The anterior spinous rays are supported by a strong triangular bone or 
plate, in addition to the strong interspinous rays. The caudal fin is large, deeply 
bilobate, and the outer rays of each lobe, which are the longest, are supported by 
a number of imbricating rudimentary rays. 
The pectoral fin is broad, but short, consisting of about twelve rays. It is 
attached to the pectoral girdle at one-third the height of the body from the 
abdominal surface. A process from the pectoral arch descends obliquely back- 
wards, and supports the ventral fin midway between the head and the anterior 
rays of the anal fin. A second horizontal pubic bone extends from the fin to the 
abdominal extremity of the pectoral arch. The ventral fins are not preserved. 
