DAVIS : HETEEOLEPIDOTUS. 
405 
fourth of the part exposed, is overlapped by the succeeding scale. 
The scales enveloping- the dorsal region are smaller but of similar 
form to the median ones, except at the base of the dorsal fin where 
they are somewhat elongated. Those on the ventral surface are as 
long as those on the lateral line but they are not more than half the 
breadth, and in a few instances they assume the form of an elongated 
triangle. The scales on the posterior surface of the body are smooth 
and the overlapping edge of the scale is not serrated. 
The dorsal fin is large, extending nearly 3 inches from the body. 
It occupies a position opposite to the interval between the ventral 
and dorsal fins ; the insertion of its anterior rays being 8 inches from 
the snout. Tweuty-foiu" rays are preserved. The anterior one is 
longest, and is divided by numerous transverse joints, about an inch 
from the base, the rays thicken and then divide into two branches, 
these again dichotomize, so that the distal ends of the fin-rays are 
divided into four and sometimes eight filamentous branches each of 
which is composed of numerous ossicles with transverse articulations. 
Fulcral scales do not appear to have been present. 
HhQ pectoral fiiis are large and powerful: 2*5 to 3'0 inches in 
length. In the specimen represented on pi. XXII the posterior portion 
is folded over so that the full size of the fin is not seen. It is com- 
posed of 18 to 20 rays, the base of these is expanded with a joint- 
like surface for articulation to the pectoral arch, some of the bones of 
which are preserved and shewn on the figure between the pectoral 
fin and the branchiostegous plates. A number of small scales 
occupying the surface of the body at the base of the fin, similar, but 
more elongated than those of H. latus described by Sir. P. Egerton. 
The basal portion of each fin-ray is smooth and fluted to the extent 
of about 1 inch; beyond that distance they become numerously 
jointed and repeatedly dichotomize as in the dorsal fin. There is no 
appearance of fulcral rays. The opposite pectoral fin is exposed, 
much disturbed and broken, a portion of the rays are bent over 
towards the head. 
A portion of each ventral fim> is preserved, but neither perfectly 
they are situated opposite to the anterior insertion of the dorsal fin ; 
the rays are strong and were powerfully attached, and by inference 
