500 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
construction of the rays is similar to that of the dorsal fin. The caudal fin is 
deeply forked, the extremities of the two lobes being 6:0 inches apart. The 
outer rays of each lobe are thick and strong; they are supported by a number of 
rudimentary imbricating rays. 
The pectoral fin is large, consisting of more than thirty rays. It is attached 
at a distance of 1:5 inch from the abdominal margin on the lateral surface of the 
body. Ventral fins not present. The scales are imperfectly preserved; they 
were large. A number of ridges extend diagonally from left to right across 
the specimen, which probably mark the impress left by the internal surface 
of the scales, as in the genus Microdon. 
This species differs from Palzeobalistum goedelii, Heckel, in the form of the 
body and the teeth. In the latter the teeth are small and have a notch on the 
upper surface. The teeth of this species are much larger, and have a flat, smooth 
surface. The form of the posterior part of the body in P. goedelii is more regular 
than in this: taking the vertebral axis as a base, the dorsal and ventral outlines 
form equal or nearly equal angles with it above and below. In the species now 
described, the angle formed by the spinal column and the dorsal margin is very 
acute, whilst that of the ventral surface descends almost perpendicularly at right 
angles with the vertebral column. 
A second specimen of this species is imperfect, only the posterior portion of 
the body, part of the dorsal and anal fins, and the caudal being preserved. A small 
portion of the head, sufticiently to indicate its position, and of the pectoral fin, 
are preserved. The vertebral column consists of about the same number of 
vertebrze as does that of Paleeobalistum goedelli, Heckel. Its size is also about 
the same ; the neural and interneural spines are shorter than in the species already 
described ; but the hemal and the interhaemal spines are very much longer, 
with the result that the portion of the body below the vertebral column is greatly 
extended. Both the interneural and the interhemal spines possess broad wing- 
like processes on the anterior margin similar to those of Microdon elegans, Agassiz. 
The abdominal margin of the fish descends almost vertically, with a slightly 
rounded flexure from the short peduncle of the tail; and with the line of the 
vertebral column forms an obtuse angle, whilst that of P. gcedelli is decidedly 
acute. The tail, from the part preserved, is much shorter. 
The evidence left by the pleurolepidal character of the scales, in the form of 
impressions of the solid bony ribs, extending transversely over the apophysial 
elements as well as the vertebral column, indicate that the scales were much 
smaller than those of the species described above; they are less than 0:1 of an 
inch across. The rays of the dorsal and anal fins are broadly expanded at the 
base where attached to the interhemal spines; for a short distance they are 
simple, bat speedily dichotomize. 
The great depth of the abdominal portion of this specimen distinguishes it 
