474 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
The vertebral column can be readily distinguished, and is well ossified; its 
component vertebrze in the region between the pectoral and ventral fins are less 
than 0:1 of an inch in length; the diameter is slightly smaller than the length. 
There are 29 vertebree between the head and the ventral fins; an additional 14 
to the anterior insertion of the first dorsal fin, thence to the root of the tail 
there are 50, and in the portion of the tail preserved there are 16, and about 
the same number is required to complete the axis to the end of the tail, giving 
a total of 125 vertebre. 
The head is remarkably small: from the tip of the snout to the occiput is 
0-8 of an inch; the depth of the cranium 0°45 inch. The mouth is hidden. The 
elevation of the head above the matrix appears to indicate that its component 
parts—the jaws and cranial members—were of dense cartilage, if not osseous. 
Between the head and the pectoral arch a number of small bones, somewhat 
displaced, appear to indicate the branchial arches. 
The pectoral fins are 0°8 of an inch in length. The pectoral arch is well 
developed and the fins supported by 16 to 18 osseous rays. The second specimen 
(Pl. x1v., fig. 3) exhibits the pectoral fins in greater perfection, as well as the 
bones of the pectoral arch. The osseous fin rays are 0-2 of an inch in length. 
The ventral fins are similarly constituted, smaller than the pectorals, and two 
inches behind them. 
The first or anterior dorsal fin is located 1:2 inches behind the ventrals, its 
anterior insertion being slightly behind the termination of the ventrals. It is 0-7 
of an inch in length, posterior margin rounded, and does not possess a spine. 
The second dorsal fin is slightly larger than the first, but in other respects 
similar. Both are covered with dermal ossicles like the body. The anal fin, as 
already observed, cannot be seen. The caudal fin is not large, nor apparently so 
powerful as is usually found in sharks. It is 1-7 inches in length. The vertebra 
are prolonged to the upper lobe, which terminates in a somewhat peculiar manner, — 
as though the end had been removed, leaving a square termination. The lower 
lobe of the tail is formed of a membranous extension of the upper, supported by a 
series of osseous or semi-osseous spinous processes from the vertebral column. 
The lower lobe has its origin two inches from the posterior caudal extremity, 
extends 0°15 of an inch from the body-line, and gradually tapers off backwards. 
The second specimen already referred to (PI. x1v., fig. 3) exhibits the under 
surface of the body. It is not perfect, but the head and pectoral fins are 
well exposed. The specimen was as nearly as possible the same size as the one 
already described; the diameter between the expanded pectoral fins is 2°2 inches. 
The under surface of the head is 0:8 of an inch in breadth, equal to nearly 
double the height of the lateral exposure of the specimen described already. 
The mouth is moderately large; the snout extends 0°25 of an inch beyond the 
anterior extremity of the mouth; it is obtusely rounded. The teeth, which are 
