536 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
0-6 of the total. The height of the body is 1:7 inch; its form a compressed 
spheroid. 
The only part of the head preserved consists of the lower part of the 
operculum and the cheek plates, and traces of the branchiostegal rays. The 
operculum is rounded posteriorly, somewhat thickly enamelled; where the enamel 
has been removed the impression of the under surface of the plate exhibits 
radiating lines, with forking branches. The branchiostegals are comparatively 
small. 
The vertebral column consists of twenty-five vertebrae; of these twelve are 
caudal. They are fully 0:1 inch in height; the length is a little less than the 
height; the central part of each vertebra is contracted. The ribs are short, but 
strong. The neural apophyses are short, straight, and strong. The interneural 
spines are longer than the apophyses, and afford a firm support to the spinous 
and soft rays of the large dorsal fin. The hemal and interhemal spines are 
similar to the neural, excepting that the four anterior interhzemal spines coalesce 
and form a large and thick bony mass, extending from the ventral surface far 
towards the vertebral axis of the body, and affording a firm base of attachment to 
the anterior spinous rays of the anal fin. The caudal termination of the vertebral 
column is slightly turned upwards, and affords a point of attachment for a 
radiating series of strong processes, which support the caudal fin. 
The unpaired or vertical fins are all strong, and well protected by spinous 
rays. The dorsal fin may not be entirely preserved (see Pl. xxvit., fig. 5); there 
are six anterior spinous rays, curved backwards and slightly pointed, and ten 
soft articulated rays. The fin extends from a point which cannot be far removed 
from the occipital region of the head almost to the base of the tail. The longest 
rays are 0°8 inch in length near the middle of the fin, where the spinous and 
soft rays join. The anterior rays of the anal fin are beneath and opposite to 
the middle of the dorsal fin; they are separated by a distance of 1:1 inch from the 
ventrals. ‘The first four rays are spinous; the fourth is the longest, 0°65 inch, 
the three in front diminishing in length to the first; the four form a closely 
imbricating triangular mass, with a sharp point and curving slightly backwards, 
which would serve as a powerful weapon of offence or defence. In addition to 
the spinous rays there are eight articulated ones, thick and strong at the base, but 
subdivided towards the distal extremity, and diminishing in size backwards. The 
anal reaches to the base of the caudal fin. The latter is large, deeply bilobate, 
twelve rays forming the upper lobe, and thirteen the lower; they are close, thick, 
divided by short transverse articulations, and dichotomizing. The entire length 
of the fin is hidden in the matrix; it was probably quite 0:8 inch. A number of 
rudimentary rays support each lobe of the fin, the first of which is a thick spine, 
sharply pointed, and separate from the succeeding ones. 
The pectoral fin is only indicated by an impression; it is situated midway 
