600 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
M. yon der Marck (‘‘ Fische, Krebse und Pflanzen aus dem Kreide in West- 
phalen,” p. 28) instituted the genus Ischyrocephalus, which is distinguished, 
amongst other things, by the fish possessing four dorsal plates extending back- 
wards from the head; the plates are elongated and pointed at each end, and, 
unlike those of Eurypholis, are not imbricated. The series of lateral plates or 
scutes, which MM. Pictet and Humbert describe in Eurypholis, are entirely absent 
in this genus. 
Pantopholis dorsalis, Davis. 
(Pl. xxxv1., fig. 2.) 
The specimen is imperfect, and is the only one I have seen possessing the 
same characters; it, however, offers several peculiarities which are considered of 
sufficient importance to render necessary the institution of a new genus for its 
accommodation. The part of the fish preserved is 7° inches in length; of this 
the head comprises 3:2 inches, the remainder being the anterior portion of the 
body. The head is displaced, so that the cranium is at the base, and the jaws 
occupy the superior position; it has evidently by some means become twisted ; 
only one fin is exposed, a large pectoral ; the caudal, anal, ventral, and dorsal fins 
are absent. Along the whole length of that part of the back which is preserved 
there is a row of elongated oval plates, irregular in size, varying from 0:2 to 0-4 
inch in length, and averaging 0°13 inch in width. Twelve plates can be counted, 
and there were probably six or eight others between the anterior one preserved 
and the head, this part of the specimen being defective. Posteriorly the fish is 
entirely gone, so that it is impossible to say whether the plates extended to the 
tail. The posterior portion of each plate is rounded and depressed; the anterior 
part, being slightly elongated, extends over the flattened posterior portion of the 
preceding scale. 
The fish, when perfect, was probably 13 or 14 inches in length. Its ravenous 
uature is indicated by the presence of the bodies of two fishes in the abdominal 
cavity. The enclosed skeletons are those of young specimens of Osmeroides ; 
the head of each is about an inch in length, and the entire fish 4 or 5 inches. 
On account of the peculiar position of the head its size and proportionate 
measurements can only be given approximately. From the tip of the snout to 
the posterior margin of the opercular plates, in their present position, is 3°2 
inches, and the posterior portion of the head is 1°8 inch; from that width the 
outline rapidly converges to a point at the snout. The maxille are strong, 
2:0 inches in length, and armed with a series of conical pointed teeth 0-2 inch in 
length. The branchiostegal rays are twelve in number on each side, long, curved 
posteriorly, and separated by about 0-1 of an inch from each other. The opercular 
bones, somewhat crushed, are large and thickly enamelled; where the latter has 
