r 
518 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
latus by the stoutness of body, shortness of snout, and color. Thirty- 
eight specimens were collected at San Diego, Cal., by the Hassler expe- 
dition. 
Rhinobatus spinosus. 
Giinther, 1870, Cat. Fish. Brit. Mus. viii, 518. 
Anterior nasal valve not dilated laterally. Snout much produced, the 
distance between the outer angles of the nostrils being one-half of that 
between the mouth and the end of the snout. The rostral ridges are 
confluent, very narrow, with a very small and short groove at the base, 
and in their entire length provided with spines. Mouth nearly straight. 
Compressed spines with dilated base along the median line of the back, 
on the shoulder, and above the eye and spiracle; the entire upper sur- 
face rough. Snout white. (Giinther.) 
Mexico. 
Rhinobatus horkelii. 
Miiller & Henle, 1841, Syst. Beschr. Plagiost. 122. 
Rhombie. Disk, including ventrals, 19, width 11.62, tip of snout to 
mouth, 6.87, and total length 35.5 inches. Head broader than that of 
R. undulatus; crown flat. Anterior margins slightly sinuous. Angles 
and posterior margins of pectorals broadly rounded. Margins of ven- 
trals nearly straight. Snout long, rather less than four times the width 
of the head between the eyes. Rostral cartilage strong; ridges distant 
at base, close together somewhat less than half their length, expanded 
near the extremity. Eye smaller than the spiracle. Spiracle with two 
folds on the posterior border. Anterior nasal valve not dilated, not ex- 
tending half the length of the nostril. Mouth nearly straight; a pair of 
coneave curves meet to form alow arch on the symphysis. Covered 
with Shagreen above and below. A row of hooked spines along the 
vertebrae, a row of several near the middle of each half of the shoulder- 
girdle, and a few smaller ones on the orbital ridge and in a group upon 
the end of the snout. Tail depressed, with a fold on each side. Second 
dorsal distant from the caudal less than the length of its base, and from 
the first less than the length of its anterior border. 
Uniform light grayish or olivaceous brown, without cloudings or spots. 
Whitish below. Translucent spaces on the snout white in young, darker 
in old. Sometimes a small patch of brown under the tip of the snout. 
Bahia; Rio Grande; Rio Janeiro and northward. 
Rhinobatus undulatus. 
v. Olfers, 1831, Die Gattung Torpedo, 22. 
Rhombie. Disk, including ventrals, 18, width 10.75, from tip of 
snout to mouth 5.75, and total length 33 inches. Anterior margins 
nearly straight, slightly concave. Angles and posterior margins of pec- 
torals broadly rounded. Posterior margin of ventral straight a portion 
of its length; posterior angle blunt. Head moderate; crown concave. 
