252 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
upper parts of the body, but they are not evenly distributed, and in 
most regions they are placed quite wide apart. They are largest and 
most numerous on the nasal ridges, interorbital space, middle region of 
back and tail, and anterior part of pectorals. On the base and edges of 
the pectorals and on the ventrals the prickles are few and small. On 
the middle portion of the pectorals they are rather numerous. Under- 
side of disk everywhere prickly except along the edges of the fins; the 
prickles largest under the snout. 
Male not seen, probably differing, as in the other species, in the sparser 
prickles above, in the absence of a lateral caudal series, and in the pres- 
ence of stouter prickles on the anterior part of the pectorals and of claw- 
like spines on the posterior part. Mouth somewhat arched. Teeth 
about #8. Nasal flap rather less than half the width of the mouth. 
Coloration essentially as in Raia binoculata. Light brown above, 
vaguely mottled with paler; the usual dark ring at the base of the pec- 
torals most distinct in fresh examples, and probably in the young. 
This species is known to us from three examples. Adult females, 26 to 
29 inches in length. One from Monterey Bay and two from San Fran- 
cisco Bay. The one from Monterey was referred to in our description 
of Raia stellulata as a long-nosed form or variety of Raia binoculata. 
Raia rhina, is related to Raia coopert and Raia binoculata. From the 
latter it differs in the much sharper and longer snout, in the less concave 
interorbital space, and in the much greater roughness of the body, the 
small prickles, even in the female of I. binoculata, being confined to the 
snout, interocular space, and a portion of the median region of the back 
and the tail, the fins being perfectly smooth. The male has the usual 
patches on the pectoral fins, and the back almost or quite smooth. 
From Raia cooperi, Raia rhina ditfers in the much smaller size in length, 
the adult of Raia cooperi reaching at least a length of more than six feet. 
It also differs in form, color, interorbital width, armature, &e., as will 
appear from the following description of a young male example of Raia 
cooperi, 274 inches in length, from San Francisco. 
Disk broad, its widest part much behind the middle, the pectoral angle 
rather sharp, and the posterior edge very little convex. ‘The anterior 
margim of the pectoral is at first slightly convex, then concave, then, op- 
posite the eyes, again very slightly convex, then again slightly concave; 
the snout itself not very sharp, although long. 
Interorbital space very broad and almost flat (deeply concave in RA. 
binoculata), only slightly depressed in the middle, the nasal ridges well 
separated for usually two-thirds their length. Supraocular ridge not at 
all elevated. Eyes quite small, shorter than the spiracles. 
Ventral fins not deeply emarginate (becoming more deeply emarginate 
in the adult). Caspers, in this example (which, although larger than 
the adults of the other species, is evidently immature), very small, 
scarcely exserted beyond the ventral edge. Claw-like pectoral spines 
not yet developed. Caudal fin wanting. Dorsal fins moderate, not far 
