50 
Memoirs of the Indian Museum. 
[VOL. II, 
Length from anterior border of anus to anterior border of 
d 
9 
disk 
86’0 mm. 
59'0 mm 
Length of tail 
89-0 
) y 
55-0 
y y 
Maximum width of disk 
79-0 
) y 
56-0 
y y 
, , thickness of disk 
25-0 
y y 
24-0 
y y 
Distance between the eyes 
6-0 
y y 
5'5 
y y 
, , from e3^es to anterior border of disk 
20 
y y 
130 
y y 
Height of dorsal fin 
7-0 
y y 
6-5 
y y 
Length of dorsal fin 
7-0 
y y 
6-0 
y y 
Owing to the strong muscles of the disk, it is liable to undergo great changes in 
shape ; the two specimens I have examined exhibit this very clearly. The degene- 
racy of the pectoral fins causes the disk to terminate, when viewed from above, some 
little distance in front of the anus. 
The mouth, as in Astrape, is to some extent protrusible, but cannot be thrust out 
bodily as a tubular structure like that of Narcine. 
The number of the type ( ) in the Museum register is F. ' . 
Family MYLIOBATIDÆ. 
Head distinct from disk, with a prominent snout or a pair of processes on the front 
of the head supported by two groups of cartilaginous jointed rays (cephalic fins) ; 
skull rectangular and box-like. Teeth flat, rectangular and pavement-like, large. ' 
Disk wide in proportion to its length. Tail long and thin, with a dorsal fin at its 
root, with or without a serrated spine. 
Taking into consideration the great differences between the skull and teeth of 
the “ Myhobatina ” and the “ Ceratopterina,” I think it as well to follow Müller 
and Henle, and also Jordan {Guide to the Study of Fishes, vol. i, pp. 551, 559, 1905), 
in regarding them as distinct famüies, although I have not adopted the American 
name ‘ ‘ MobuHdæ ’ ’ for the latter group. 
The Myliobatidæ, if this view be accepted, consist of the genera Rhinoptera , 
Myliohatis and Aetobatis, each of which is represented by at least two species in Indian 
seas. Of Rhinoptera I have only seen the skeleton and teeth, and I do not, therefore, 
propose to discuss its Indian representatives. Of Myliohatis and Aetobatis, however, 
the ‘ ‘ Golden Crown ’ ’ has obtained large numbers of specimens, which have afforded 
invaluable material for the elucidation of several doubtful points. The three genera 
may be distinguished by the following characters: — 
I. Head provided with a pair of distinct rayed appendages (cephalic fins) on 
the ventral surface. Teeth tesselated, in five or more series, the central one 
being the broadest and the others decreasing in breadth from within out- 
wards . . . . . . , . . . . , Rhinoptera. 
II. Cephalic fins encased in muscle and skin to form a single more or less conical 
snout. 
