Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 547 
anterior and posterior margin. The latter curves gently backwards, and forms a 
short, acutely-pointed spinous process, extending over and protecting the occipital 
region of the skull. The opercular region is covered by thick plates, extending in 
an almost straight line from a position behind the orbit to the lower margin of 
the head ; they are 0°8 inch in breadth; the posterior margin circular. A plate 
extends between the opercular bones and the occipital spine already mentioned. 
The posterior portion of the armature of the head consists of an expansion of the 
pectoral arch into three prominent pointed spinous processes. The first has its 
origin behind the median portion of the operculum, and from a broad _ base 
extends backwards, with a downward curvature, to a more or less pointed apex. 
The spine is hollow; its external surface is striated, and the convex margin 
denticulated. A second and smaller spinous process is developed near the base 
of the first, and extends in an outwardly diagonal direction from the body. 
The third extends from a base, parallel with the abdominal surface of the body 
of the fish, horizontally backwards, its point passing behind the second process. 
It is striated, and has denticles similar to the first one. The upper jaws are 
preserved, and the teeth are attached. The jaws have been pressed backwards, 
and expose more of the under surface than they would in a natural position. 
There are two rows of palatal teeth, with flattened crowns, on each ramus of the 
jaw, which completely cover the palatal surface; they are large posteriorly, and 
diminish in size as the front of the mouth is approached. In addition to the four 
rows mentioned by Prof. Pictet, there are a considerable number of small teeth 
occupying the extremity of the jaws. A portion of the lower jaw is exposed; it 
extends 18 inch backwards; it is strong, pustulate on the outer surface, and 
furnished with similar teeth to those of the upper jaw. 
The vertebral column is exposed to the length of 3°5 inches; the osseous 
centres, if any existed, have disappeared, leaving only the external coating of 
the column preserved. The vertebre are 0:2 inch in height and 1-5 in length; 
a number of ribs may be discovered. Neural apophyses, straight and strong, 
are attached to the dorsal aspect of the vertebra. Two inches behind the 
head the anterior rays of the dorsal fin are supported by interspinous bones. 
The extent of the fin is not shown. At a distance of 1°5 inch behind the anterior 
rays of the dorsal fin the commencement of the ventral fin exists; but this 
also is imperfect. 
Formation and Locality—Hard chalk: Hakel. 
Ex coll.—Lewis Collection, British Museum (Natural History Department), 
London. 
