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BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



Color grayish, the disk with scattered dark specks; plain pale 

 underneath. 



This species is related to U. peruanus, with which it agrees rather 

 well in shape, though the tail is a little longer. It differs, further, in 

 the absence of spines and prickles on the disk; in the wider, distally 

 rounded caudal fin; and in the absence of cusps on the teeth. It 

 differs from U. aspidurus (Jordan and Gilbert) in having a shorter 

 tail (longer than disk in aspidurus); in the notably less strongly 

 exserted snout; the larger eye (about 8.5 in snout in aspidurus); and 



f 



Figure 13. — Uroirygon serrula, new species. From the type, 187 mm. long, Lobos de 

 Tierra Bay, Peru (U.S.N. M. No. 127795). Insert, diagram of outline of snout and 

 position of mouth and nostrils. 



in the notably differently shaped ventral fin, which has a nearly 

 straight distal margin with the outer (lateral) part somewhat produced 

 (about 4.0 in length anterior to axil of pectoral in aspidurus). From 

 U. chilensis (Giinther), according to the description and figure, it differs 

 in the narrower disk (1,57 in total length in chilensis); and the tail is 

 shorter, although it is described as longer than the disk in chilensis, and 

 it seems to bear a broader and more broadly rounded caudal fin. It 

 differs from the type of U. goodei (Jordan and Bollman) in the dif- 



