54 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



beginning again on posterior part of back, and becoming numerous 

 and strong on the dorsal surface of tail, forming a more or less definite 

 lateral series of spines on distal part of tail ; no spines on disk, a median 

 series beginning somewhat in advance of axil of pectoral, extending 

 on the tail, the last one being between the dorsal fins; two dorsal fins, 

 about equal in size, separated by a distance nearly half as long as base 

 of fin, the second one separated from the moderately well-developed 

 rudimentary caudal by a distance fully half as great as base; base 

 of first dorsal 4.35 in snout; ventral very deeply notched, the inner 

 part narrow and strongly convex, outer lobe 4.45 in length anterior 

 to axil of pectoral, 6.45 in width of disk. 



Color brownish, with pale spots, several small ones mostly near 

 the margins of the disk; a pair of rather larger ones toward margins 

 of disk opposite spiracles, a pair of considerably larger ones opposite 

 nuchal region, and a third pair of still larger ones farther back on 

 the disk, the spots on each side of median line of back of the three 

 pairs being in a straight longitudinal row. 



The foregoing description is based on the type, a female 472 mm, 

 long, according to my measurement (480 mm. in original description). 

 This specimen differs prominently from the others at hand in the very 

 deeply notched ventral fins; the large eye; and correspondingly narrow 

 interorbital. According to Norman's revision of this genus and Raja 

 (1937), in which this species apparently was not considered, it seems 

 to be most nearly related to P. scorbina (Philippi), from which it differs, 

 however, in several respects, as follows: The vent is a little nearer 

 snout than tip of tail; the opposite holds for scorbina. The inter- 

 orbital space is only a little less than the combined longitudinal length 

 of eye and spiracle; equal to or only a little greater than diameter of 

 eye in scorbina. Internarial space is broader, 2.1 in preoral length: 

 2.5 to 3.0 in scorbina. Dorsal fins are well separated, with a spine 

 between them; close together or more usually connected in scorbina. 

 No nuchal spines present; three or four nuchal spines in scorbina. 

 Finally, whereas the lower surface has a broad band of prickles along 

 anterolateral margins of disk in aguja it is rather smooth in scorbina. 



It is judged from the original description and especially from the 

 figures that the paratype of Raja aguja probably is a different species. 

 Beebe and Tee-Van (see references above) have suggested that it may 

 even belong to a different genus. However, William C. Schroeder 

 has kindly examined the paratype, which is in the Museum of Com- 

 parative Zoology, and has reported that the cranium is not prolonged 

 into the snout. Therefore, it seems to be a Psammobatis, though 

 probably not P. aguja. If it is not P. aguja, it may represent an 

 undescribed form. 



Range. — As here understood this species is known only from the 

 type (U.S.N.M. No. 65641) taken by the Albatross near Aguja Pomt, 

 Peru. 



