1909.] 
N. AnnandaIvE : Report on the Batoidei. 
23 
dp of the snout ; while in the adult this point is situated at nearly four-fifths of 
the distance. All the proportions of the disk, however, are variable. The angle of 
the snout is rather variable but in fresh specimens it is, as a rule, slightly less than 
a right angle; in the unborn young it is, at any rate in some specimens, obtuse. 
The length of the snout, measured from the eyes, is about | of the total length of 
the disk in the adult and between ^ and in the young. The outline of the front of 
the disk is somewhat sinuous in the adult but forms almost a simple concave 
curve in the young. 
Fig. 2. — Diagram showing the difference in outline between the young (A) and the adult (B) of 
Trygon uarnak. 
Eyes large and prominent, especially in the young. The dorsal wall of the spiracle 
forming a convex longitudinal flap. 
TaU^ more than twice as long as the disk, cylindrical, tapering, armed with a single 
rather slender serrated spine, which is situated much nearer the base than the 
tip of the tail. No cutaneous folds above or below. 
Skin tough. In the young there are as a rule several relatively large rounded 
tubercles in the mid-line of the scapular region, and these, although at first 
they are sometimes practically alone, are usually surrounded by smaller, heart- 
shaped, nearly flat denticles which have the narrower end pointing backwards. 
In the adult the middle of the back is somewhat sparsely covered with similar 
but relatively smaller denticles, with which are interspersed numerous small, 
spiny ones with stellate bases. These become more numerous on the posterior 
part of the disk and the base of the tail, which is completely surrounded by little 
almost granular denticles with the spiny denticles scattered among them. This 
arrangement is continued for the whole length of the tail. There are no denticles 
on the periphery of the disk or on the ventral surface, but those on the back do 
' In a large proportion of the larger specimens of the genus Trygon the tail is mutilated ; it is often 
difficult to tell whether mutilation has occurred or not. 
