Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. O49 
Xenopholis carinatus, Davis. 
(Pl. xx1x., fig. 4.) 
A peculiar specimen of very great interest, but, unfortunately, very imperfect: 
the whole of the head, with the exception of some of the opercular and cranial 
bones, is absent; a large portion of the back and a part of the tail has shared 
the same fate. The length of the part of the specimen preserved is 5:5 inches, 
of which the tail occupies 0°7 inch. 
The spinal column cannot be distinguished. The neural and hemal spines 
in the posterior part of the body are clearly seen: they are strong, and support 
interneural and interhemal spines attached to the dorsal and anal fins. The 
vertebree in this part of the body may be enveloped by the scales, but neither 
in the posterior nor the anterior portions do the vertebra make any impression, 
as they naturally would if osseous; and it is probable that the entire vertebral 
column was cartilaginous. The base of a portion of the caudal fin is preserved, 
and, though the rays are in natural position, there is no evidence of bony 
vertebra, a vacant space remaining where they once were. 
A portion of the dorsal fin is preserved; twenty-six rays can be counted, 
though in the same length only eighteen interneural spines seem to be preserved. 
The rays are simple and undivided, but are articulated, and nearly an inch in 
length. The anal fin is situated opposite to the dorsal, and near the base of the 
caudal; its base is 1‘2 inch in length; the two anterior rays are strong; spines 
0:2 and 0°25 inch in length respectively. The succeeding rays are similar to 
those of the dorsal fin, twenty-one in number, supported by fifteen interspinous 
hemal rays. Of the caudal rays fifteen can be distinguished pertaining to the 
lower lobe, but the greater part of the fin is absent. 
The ventral fin is 11 inch in advance of the anterior rays of the anal; it 
consists of twelve or thirteen articulated rays nearly 1:0 inch in length; it is 
situated on the abdominal surface. At the base of the anterior ray an external 
bony plate extends forwards 0°35 inch; its external surface is produced so as 
to form two acute points or denticles 0:1 inch in height. The pectoral fin cannot 
be distinguished. 
The scales of the head and body are large, solid, bony plates. At a distance 
of 2 inches from the tail there are eight scales in a transverse line, and from 
the tail in the same distance there are ten scales along the lateral line. The 
scales are more or less angular in form; their greatest diameter at right angles 
to the vertebral axis is 0°35 inch; the opposite diameter parallel with the lateral 
line is 0°3 inch. The median surface of the scale is raised in the form of a 
ridge, extending to the posterior part of the scale, which is produced so as to 
form an obtuse angularity; from this the margin recedes, forming concave 
outlines; the posterior margin, which is not exposed, is triangular, with straight 
TRANS. ROY. DUB. SOC., N.S. VOL, II. 4F 
