POTAMOTRYGONIDAE. 415 



more angular on old males. Length of snout from eyes greater than distance 

 between spiracles. Tail from the pores one third the length of the body from 

 the same point, with a well-developed fold above and a wider one below. Caudal 

 spines present on the' embryo before extrusion. No tentacle behind the spiracle. 

 Adults are rather more angular forward than most other species and the disk 

 as a whole is more of a triangle. 



Large specimens dark brown marmorate with lighter; young lighter to 

 ashy with lighter marmorations and whitish spots. 



Off Californian coasts. 



Pteroplatea altavela. 

 Plate 53. fig. 6 (pelvis); Plate 57, fig. 3 (heart); Plate 72 (skeleton). 



Pastinaca marina altera wTepvirXaTeta, Altavela dicta Columna, 1616, Aquat., C 2, p. 4, pi. 2; Willughby, 



1686, Pise, p. 65, pi. cl, f. 3; R.\y, 1713, Pise, p. 24. 

 Raia altavela Linne, 1758, Syst. nat., 1, p. 232; Gmelin, 1789, Linne Syst. nat., 1, p. 1509. 

 Raia pastinaca /? Altavela, Linne, 1766, Syst. nat., 1, p. 396. 

 Dasyatis attavilla Rafinesque, 1810, Ind. itt. Sic, p. 49. 

 Trygon altavela Lowe, 1839, Proc. Zool. see. London, p. 92; Bonaparte, 1841, Icon. Fauna Ital., Pcsci, 



fig. 

 Pteroplatea altavela Muller & Henle, 1841, Plagios., p. 168; Dumeril, 1865, Elasm., p. 611; Gunth., 



1870, Cat. fishes Brit, mus., 8, p. 486; Ribeiro, 1907, Arch. Mus. nac, 14, p. 181. 

 Pteroplatea canariensis Valenciennes, 1843, Ichth. Canar., p. 100, pi. 23, f. 1; Dumeril, 1865, Elasm., 



p. 611. 

 Pteroplatea valencienni Dxjmeril, 1865, Elasm., p. 612; Garman, 1888, Bull. M. C. Z., 17, p. 101, pi. 44, 



45. 

 Pteroplatea vaillaniii Rochebrune, 1880, Bull. Soc. philom., ser. 7,4, p. 159; 1882, Acta Soc. Linn. 



Bord., 36, p. 54, pi. 2. 



A tentacle behind the spiracle. Length of snout, on young, less than the 

 distance between the spiracles. Width of disk twice its length, including the 

 ventrals. Length of the tail from the abdominal pores little less than half that 

 of the body. Tail with a narrow fold above and another below behind the spine. 

 No dorsal fin. 



Back brown, marmorate or vermiculate with lighter; tail brown with about 

 six transverse bands behind the spine. 



The figure of P. vaillantii from Senegambia shows straighter margins, 

 sharper angles, and coarser marmorations; manifest inaccuracies in other 

 respects induce uncertainty as to how much reliance is to be placed on these 

 items. 



Tropical Atlantic; Mediterranean; Brazil. 



POTAMOTRYGONIDAE. 



Body, head, and pectorals much depressed forming a broad rounded disk. 

 Pectoral fins meeting in front forming the snout, without a supporting rostral 



