604 Davis— On the Fossil Fishes of the Chalk of Mount Lebanon. 
backwards at a much more acute angle. A series of epipleural spines extend 
transversely from the neural spines as well as from the hzmal spines presently to 
be mentioned. Interneural spines, eighteen in number, support the rays of the 
dorsal fin; they are stronger than the neural spines, and their upper extremities 
are expanded for attachment to the rays of the fin. The hemal spines are similar 
to those of the posterior neural ones, except that their extremities are curved 
backwards to a larger extent. Interhzmal spines support the anal fin; they are 
eighteen in number, and similar to those supporting the dorsal fin. The ribs are 
strong, simple, an inch to an inch and a-half in length, and extending apparently 
to the abdominal surface of the body. 
The anterior rays of the dorsal fin are 2 inches behind the head; the base of 
the fin extends 1:7 inch, and its posterior ray is separated by about 3 inches from 
the base of the tail; it is composed of fifteen strong rays; the anterior one is 
longest, being for a length of 1 inch undivided ; beyond it branches into smaller 
rays; the succeeding rays are gradually reduced in length. 
The anal fin is, like the dorsal, large and powerful; its base is 1°75 inch 
in length, and is separated from the caudal fin by a space of 0°75 of an inch. 
The fin-rays are shorter but somewhat more robust than those of the dorsal fin; 
towards the extremities they are subdivided to a considerable extent. 
The caudal fin is large, each lobe 2 inches in length and deeply forked, the 
whole consisting of twenty rays, with rudimentary rays supporting both the upper 
and lower lobes, eight in number, attached to the former, and seven to the latter. 
The external ray of each lobe is remarkably thick and strong, 0°12 inch in 
diameter in the central portion, but tapering slightly towards the extremity; the 
succeeding rays are thinner, and diminish in length rapidly towards the median 
portion of the fin. The rays, except the large external ones, repeatedly dichoto- 
mize, assuming a filamentous character at their extremities; the external rays are 
enveloped in a series of imbricating sigmoidally-shaped plates, represented on 
Pl. xxxvi., fig. la. 
The pectoral fins are situated immediately behind the opercular apparatus on 
the abdominal surface of the body, and are attached to a strong series of bones 
forming the scapular arch, but which cannot, in the specimens available, be 
separately identified. Each fin is composed of twelve rays, and is 1:6 inch in 
length; the basal half of the rays is simple, beyond they are divided. The 
distal extremity of the fin is rounded, the fourth and fifth rays being the 
longest. 
The ventral fins are 1°5 inch behind the pectorals, and are separated by a 
distance of 2°5 inches from the anterior ray of the anal; they are on the abdominal 
surface 0-2 of an inch apart, and are connected by transverse osseous processes 
which, as well as the pubic bones, 0°5 of an inch in length, meet triangularly on 
the median line. The ventral fins apparently contain about the same number of 
