THE SHORE FISHES OF PERU 75 



Disk nearly twice as wide as long; pectoral extending forward to 

 below posterior margin of eye, its anterior margin almost straight 

 nearly to tip, its distal margin very broadly and gently concave, its 

 outer angle round, its posterior angle somewhat narrower, length 

 anterior to margin of posterior angle of pectoral 1.95 in width of disk; 

 length anterior to axil of pectoral 2.05; length anterior to vent 2.1; 

 tail very slender, whiplike, a little more than twice the length of disk, 

 rather broad and depressed at base, its width at axil of ventral rather 

 more than 1.5 times its depth at same place, and rather less than 1.5 

 times longitudinal diameter of eyeball, bearing a serrated spine (miss- 

 ing in the specimen at hand); spine preceded by a small dorsal fin; 

 snout broadly rounded, its length to eye 5.15 in length anterior to 

 vent, its length to mouth 6.1; internarial space 8.8; nostrils with a 

 continuous fringed flap, with slightly concave margin; mouth trans- 

 verse, its width 1.1 in interorbital; teeth flat, the middle ones trans- 

 versely elongate, with three or four square ones on each side; ventral 

 broadly convex, its anterior margin 4.25 in length anterior to vent; 

 ciaspers very small in specimen at hand, shorter than ventral, very 

 probably immature. 



Color of old preserved specimen uniformly grayish brown above; 

 pale underneath. Described by Evermann and Radcliffe (see reference 

 above), when the specimen had been in alcohol a much shorter time, 

 as follows: "Dusky brown, a light line originating under middle of 

 spiracle, extending backward along base of pectorals, from this 10 

 or more transverse lines extending across pectorals, these narrow 

 bands or lines have well-defined edges but differ so little in coloration 

 from the ground color as to be easily overlooked; ventral surface 

 light." 



The description is based on the only specimen available (U.S.N.M. 

 No. 77700), a male, purchased from fishermen by R. E. Coker at 

 Paita, Peru, July 22, 1908. The specimen has a total length of 995 

 mm. and a width of 440 mm. and is the same specimen described as 

 Myliobatis californicus by Evermann and Radcliffe (1917, p. 17). 

 However, Garman (1913, p. 430) recognized a Peruvian specimen 

 as distinct from A. californicus, giving it the name Myliobatis peru- 

 vianus. The specimen now at hand agrees essentially with Garman's 

 description and figures. It is not clear, however, from Garman's 

 account just wherein peruvianus differs from californicus, and its 

 distinctness has been questioned. 



The Peruvian specimen now has been compared with two specimens, 

 also males (U.S.N.M. Nos. 93098 and 61231), 282 and 313 mm. wide, 

 from San Diego and from San Pablo Bay, Calif. As the specimens 

 are unequal in size the comparison is not altogether satisfactory. It 

 seems improbable, however, that the rather numerous differences 

 noticed are all due to the differences in size and age. 



