68 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



The description is based on the type (U.S.N. M. No. 127790), a 

 female 188 mm. long, taken with a seine in Independencia Bay, and 

 a paratype, a male 162 mm. long, caught in a dredge in Sechiira Bay. 

 The proportions based on the type are given first in each instance. 

 Both specimens were secured by the Mission. 



In addition to the type and paratype, there are at hand three 

 embryos, 118, 119, and 121 mm. long, also secured by the Mission, 

 which were removed from a female taken in Independencia Bay. 

 Unfortunately, the parent is not at hand, and the embryos cannot 

 be identified with any degree of certainty with the present species 

 and therefore should not be regarded as paratypes. The embryos 

 were placed here principally because their general shape agrees, the 

 caudal fins are identical in width and shape, and the ventral fins, too, 

 seem to agree fairly well. The embryos do not agree, however, in 

 color, as they are plain brownish, and of course no spines or tubercles 

 are developed. The teeth in the embryos are fairly well formed, the 

 caudal spine is covered with skin, though serrations are visible, and 

 behind the eye and on the inner margin of the spiracle is a high coiled 

 fold of skin, which evidently is an embryonic character. A similar 

 structure is present also in an embryo removed by the writer from a 

 female U. asterias (Jordan and Gilbert) taken in Panama Bay. This 

 external membrane of the embryo presumably is folded downward 

 in the adult when it partly closes the spiracle, which is wide and 

 open in the embryos. 



This species is rather close to U. goodei (Jordan and Bollman), from 

 which it differs principally in having a nuchal spine, tubercles on the 

 snout, small lateral spines on the tail below the large caudal spine, 

 and small tubercles on the dorsal fin fold. In the presence of lateral 

 spines on the tail and tubercles on the dorsal fin fold, it seems to differ 

 from all other species heretofore described from the Pacific coast of 

 America, except U. asterias (Jordan and Gilbert) and a specimen 

 (probably of a different species) at hand from Panama Bay. It 

 differs further from the type of U. goodei, now before me, which is 

 plain brownish above, in being graj^ and having scattered dark specks 

 on the disk and basal part of tail. It differs from U. serrula in having 

 a rather rounder (less angular) disk; differently shaped ventral fins; 

 a narrower caudal fin; in the presence of a nuchal spine; and in the 

 presence of spines and tubercles on the tail, as already stated. 



The specific name was suggested by the spines on the tail. 



Range. — Independencia Bay and Sechura Bay, Peru. 



