74 



BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



line of the ventral surface of the tail and a larger one above, and in 

 the plainer color, round white spots being entirely wanting. Some 

 proportional differences are evident from table 1. 



Range. — Known only from Lobos de Afuera Island, Peru. 



Table 1. — Some proportions in three species of Pteroplatea 



Character 



micTura, 2 



specimens, 330 



and 335 mm. 



wide 



maTmorata, 2 



specimens, 157 



and 290 mm. 



wide 



afuerae, 1 



specimen, 



353 mm. 



wide 



Total length, in width of disk 



Length of disk, in width of disk 



Length anterior to axil of pectoral, in width of disk 



Length anterior to vent, in width of disk.. 



Length posterior to vent (tail) , in width of disk 



Interorbital space, in length anterior to vent 



Snout to eye, in length anterior to axil of pectoral 



Snout to mouth, in length anterior to axil of pectoral.. 



Interorbital space, in length anterior to axil of pectoral 



Interspiracular space, in length anterior to axil of pectoral.. 



Internarial space, in length anterior to axil of pectoral 



Width of mouth, in length anterior to axil of pectoral 



Eye, in interorbital space _ 



Length of clasper, in length anterior to vent 



1.25, 1.2 

 1.45, 1.55 

 1.7 , 1.75 



1.35, 



1.65, 1.7 

 1.95, 1.85 



1.75, 



4.6 , 

 6.3 , 

 3.8 , 

 3.3 , 

 6.55, 

 6.2 , 

 9.0 , 

 6.5 , 



3.7 , 

 4.75, 



1.8 



4.3 



6.0 



4.05 



3.8 



6.3 



6.1 



9.0 



6.65 



4.2 



4.4 



1.95, 

 4.9 , 

 5.65, 



4.4 , 

 4.3 , 

 5.55, 

 5.7 , 



8.5 , 

 5.3 , 

 3.1 , 



1.9 



5.55 



5.0 



4.4 



5.8 



6.0 



8.75 



6.0 



3.7 



3.6 



1.4 



1.77 



2.0 



2.1 



5.0 



5.7 



4.4 



4.4 



5.95 



6.4 



8.6 



7.0 



4.2 



4.5 



Family AETOBATIDAE: Eagle Rays 



Body, head, and pectorals forming a very broad disk; pectorals united 

 or free from rostral or cephalic fins in front of snout, the latter united 

 or appearing as two fleshy projections; tail long, whiplike, bearing a 

 serrated spine and a small dorsal fin in front of it; teeth large, flat, 

 more or less hexangular, the middle ones usually broader than the 

 outer ones; eyes prominent, lateral; spiracles large, behind eyes; skin 

 smooth. 



A single genus is represented in the Peruvian collections studied. 



Genus AETOBATUS Blainville, 1816 



Disk much broader than long; outer angles of pectoral flns acute; 

 pectorals continued as a rather narrow lobe around the snout; teeth 

 in several rows, low, broad, and flat, the median ones transversely 

 elongate, two or more times as large as the outer ones; nasal valves 

 confluent, with a broad free flap in front of mouth; ventral fins short 

 and broad. 



AETOBATUS PERUVIANUS (Garman) 



'Rato' 



Myliobatis californicus Abbott, 1899, p, 331 (not of Gill), Callao, Peru (notes on 

 specimen 470 mm. wide). — Eveemann and Radcliffe, 1917, p. 17 (not of 

 Gill), Callao and Paita, Peru (description). 



Myliobatis peruvianus Garman, 1913, p. 430, pi. 36, figs. 4-6, no locality stated 

 (original description) . 



Holorhinus peruvianus Fowler, 1941a, p. 228 (references). 



Aetobatus peruvianus Beebe and Tee-Van, 1941, p. 271, fig. 34 (references; note). 



