Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 499 
of the head, in proportion to that of the body, is much smaller in M. elegans 
than in the species now described. In the latter the orbit, though high, is 
situated at a greater distance from the anterior margin of the head. 
Formation and Locality—Hard limestone: Hakel, Mount Lebanon. 
Ex coll,—Lewis Collection, R. Damon, Esq. 
Paleobalistum ventralis, Davis. 
(PE exrmn., figs, Vula.) 
A specimen in the Natural History Museum, London, from the hard chalk, 
possesses characters which distinguish it from the more common species, Palzo- 
balistum goedelli, Heckel, and appears to render necessary the following descrip- 
tion. The fish approaches an oblong form, the anterior portion somewhat thicker 
and more rounded than the other. The body is 10:0 inches in length; the tail, 
which is widely spread in this specimen, adds 3:0 inches to the length. It 
measures 6:0 inches across the outstretched extremities of the lobes. 
The head is large, 55 inches in height and 3°5 inches from the snout back- 
wards. The bones are split, a portion having adhered to the opposite matrix, 
which renders their determination difficult. The orbit is large; it is above the 
median line, 1:0 inch from the anterior margin of the head. The opercular bones 
are long and narrow. The jaws are obscure; the dentition not present. The 
teeth are exhibited in another example; they are round, with flat surface, 0:1 of 
an inch in diameter. Their arrangement on the jaw is not shown. 
The vertebral column is large and massive, consisting of thirty -nine vertebree ; 
of this number eighteen are caudal. The vertebra are 0°4 inch in height, and 
0-2 in width. Those towards the termination at the caudal end are much smaller. 
The ribs are long, extending nearly to the abdominal margin. The neurapophyses 
are strong, straight, and long. Supporting the dorsal fin are interneural spines, 
about twice the number of the neural, longest anteriorly, and diminishing 
backwards. The hemal and interhzmal spines are similar to those above. The 
anterior interhemal spine is large, and extends considerably upwards, affording a 
firm support to the long anterior rays of the anal fin. 
The dorsal fin extends from the summit of the back to the base of the tail. 
The anterior ray is 6:0 inches from the snout and 7:0 inches from the base of the 
tail. The fifth ray is the longest, attainmg 1‘7 inch. The succeeding rays gra- 
dually diminish in length towards the tail. The first four are fulcral, and diminish 
inl ength anteriorly. One-third the length of each ray is solid; the remaining 
divided. The anal fin is 4:0 inches in length. The anterior rays are probably 
2-0 inches in length. The succeeding ones rapidly shorten to the sixteenth, and 
thence to the base of the caudal fin they gradually decrease in length. The 
