Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 489 
Rhinobatus intermedius, Davis. 
(Ei xexs figs iS) 
One side of the body of this specimen is very well preserved, the other is 
considerably displaced. ‘The presence of a clasper attached with the ventral fin 
indicates that the fish was a male, and it is exhibited with the abdominal 
surface upwards. The form of the fish is similar in some respects to that 
of Rhinobatus tenuirostris, but, as will be seen hereafter, it differs in many 
details. The anterior extremity of the head is wanting, so is the tail. The 
part preserved is 14 inches in length: of this 4°5 inches are comprised in the 
portion of the head still attached; the width of the fish across the pectoral fins 
was about 8 inches, across the ventral fins 4 inches, and at the base of the 
tail 2 inches. The body is covered with closely set minute dermal tubercles. 
The head is more or less disturbed and the separate parts displaced. The 
posterior portions of the left rami of the upper and lower jaws are preserved ; 
they are large and strong (PI. xx, fig. 1), and composed of cartilage, with 
numerous round ossifications intermixed with the substance of the cartilage. 
Between the rami is a large aggregation of teeth; they are small, with a broad 
base, from which rises a central cusp, with, in some cases, a lateral cusp on 
each side, in others only the one median denticle. The posterior portion of the 
head is occupied by a large median ossification, 2 inches in length and 0:8 
of an inch in breadth, from which depend the branchiostegal rays, five in 
number, 2 inches in length, and 0-2 of an inch in thickness. In front of the 
buceal orifice the base of a large chondroid bone of similar shape and structure 
to that giving support to the snout of Rhinobatus tenuirostris is exhibited. 
From the presence of this bone there can be little doubt that the form of the 
anterior portion of the head was much the same as in R. tenuirostris; but as 
the basal portion exhibited in this specimen is shorter and wider than the 
one already described, it may be inferred that the snout was also shorter. 
The vertebral column in the extent preserved exhibits eighty vertebree, and 
of these eighteen are comprised between the pectoral and ventral arches. A 
number of ribs, apparently twenty-four, extend from the pectoral some distance 
beyond the ventral arch ; they are small and slender anteriorly, but the posterior 
ribs are considerably thicker and longer. A number of processes extend from 
the caudal vertebre; they are not sufficiently exposed to be clearly identified. 
The diameter of the vertebra is 0°3 inches, their length is 0°15 of an inch, 
decreasing backwards. 
The paired fins are large and well developed. The pectorals extend from 
a position opposite the extremity of the mouth for a distance of 7 inches 
backwards; the longest central rays are 3-5 inches in length. The basal portion 
