1909.] 
N. Annandale ; Report on the Batoidei. 
47 
and distinct from the trunk. Kyes about half as large as the spiracles, pro- 
tuberant in life, separated l)y a concave interspace about half as long as 
their distance from the anterior border of the disk. Margins of spiracles smooth. 
Mouth surrounded posteriorly by a .semicircular fold, about half as wide as its 
distance from the anterior border of the disk, provided with thick, tuberculate 
lips, which are discontinuous in the middle of the anterior border. Teeth occupy- 
ing nearly the whole of the mandibular surface, with a broad, bluntly pointed 
transverse ridge. A bilobed, prong-like, vertical process on the roof of the mouth 
and a similar one on the floor. Nasal flap with a distinct median longitudinal 
groove and a median process on the free edge. 
Colour. — Dorsal surface dull chocolate colour with a purplish tinge. Ventral surface, 
edge of disk and fins, a large oval spot on each side of the back some distance in 
front of the posterior margin of the pelvic fins, and a forwardly directed streak 
on each side of the anterior part of the tail, cream colour. 
This species exhibits much the same variation as Narcine timlei and N . brunnea in 
respect to its fins. It has been taken by the ‘ ‘ Golden Crown ’ ’ in considerable 
numbers off the Orissa coast and appears to be common all over the Bay in shallow 
water. It is not so common as N. timlei and N. brunnea, however, and perhaps 
inhabits slightly deeper water. 
I^arge specimens measure 16 cm. in total length and 9 cm. across the disk. 
Genus BengalichthYvS , gen. nov. 
Closely allied to Astrape, from which it is distinguished by its thick, fleshy disk, 
rudimentary pectoral fins, and degenerate eyes. 
I think it well to separate a form represented by two individuals in the ‘ ‘ Golden 
Crown ” collection from Astrape as a distinct genus, in order to emphasize the peculiar 
manner in which this form has become adapted for a more or less sedentary existence. 
In several respects the adaptation is of a nature closely similar to that which has brought 
about the evolution of Benthobatis from Narcine, although the environment in which 
this evolution has taken place is not the same in the two cases. Benthobatis , as I have 
already pointed out, is a deep-sea form — it occurs at depths from about 400 to about . 
700 fathoms — and, like many deep-sea forms, has degenerate eyes. The disk, moreover, 
is thick and muscular and bears on the dorsal surface numerous little glandular pits ; 
the pectoral fins are not clearly marked off from the body. In all of these points the 
species of Bengalichthys to be described immediately resembles Benthobatis , although 
it is not a deep-sea form, having been taken in only 15 fathoms. In two striking 
characters, however, it differs from Benthobatis , viz., in coloration and in the number 
of the dorsal fins. The former difference is probably due to its environment, the latter 
to its ancestry ; in other words, the former is an adaptive character, the latter a 
morphological one. A character common among deep-sea fish of all kinds is a dark and 
uniform coloration of both the dorsal and the ventral surface, while among the rays of 
shallow water it is unusual for the ventral surface to be dark, although this is the case 
