FAMILY, IV— RAJID^. 735 



Family, IV— RAJID^. 



Disk broad, rhombic : tnbercules or spines usually present. The pectorals extend to the snout. Tail 

 with a longitudinal fold on either side. No serrated caudal spine. Electric organs absent. 



Tarrell remarks : — " Spines on the upper surface of the males occur in the different species of Skate with 

 smooth skins, and are entirely independent of those spinous productions of the cuticle which distingpiish two 

 British species." Darwin* observes of these spines, "they are only temporarily developed during the breeding 

 season." This phenomenon, so far as I am aware, has not been observed amongst the various forms of Indian 

 skates or rays. 



Geographical distribution. — Seas of both hemispheres, but more numerous in the northern, it possesses 

 but few representatives along the coasts of India. 



Genus, 1 — Platyehina, Mailer and Eenle. 



JMsh rhombic, with a fold on either side : tail distinct. Nasal valves distinct. Two dorsal fins on the tail : 

 caudal well developed : ventrals separated one from the other. Body covered with rough asperities and spines. 



OeograpMoal distribution. — Seas of India to China and Japan. 



Platyrhina Schonleinii. 



Miill. and Henle, Plagios. p. 125, t. xliv; Dumeril, Hist. Nat. Poiss. i, p. 577; Giinther, Gatal. 

 viii, p. 471. 



Disk sub-circular : snout obtuse : tail as long as the disk. Dental plate undulating : three elevations 

 in the lower and three corresponding depressions in the upper jaw. Nostrils wide apart. A row of strong 

 spines and also smaller lateral ones along the median line of the back and tail : some more along the edge of 

 the orbit and on the shoulder. Colours — brown, covered with light blotches, said sometimes to have dark cross 

 bands and large dark spots. 



Habitat.— CovomaiMA.e\ coast of India. The example described, a male, 27i inches in length, was in 

 the Madras Museum. 



» " Descent of Man," p. 331. 



