FAMILY, IV— RAJID.^. ^35 



Family, IV— RAJID^. 



Disk broad, rhombic : tubercules 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. 



Yarrell remarks:—" Spines on the upper surface of the males occur in the difi'erent species of Skate with 

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

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

 season." This phenomenon, so far as I am aware, has not been observed amongst the various torms ot Inaian 

 skates or rays. 



Geographical (Udrlbwtion.-Seas of both hemispheres, but more numerous in the northern, it possesses 

 but few representatives along the coasts of India. 



Genus, 1 — Platyrhina, Mailer and Henle. 



Disk 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. 



Geographical distrihution. — Seas of India to China and Japan. 



Platyrhina Schonleinii. 



Miill. and Henle, Plagios. p. 12o, t. xliv; Dumcril, Hist. Nat. Poiss. i, p. 577; GUnther, Catal. 

 viii, p. 471. 



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

 in the lower and three correspondin<T 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 ot 

 the orbit and on the shoulder. Co/ou/s-brown, covered with light blotches, said sometimes to have dark cross 

 bands and large dark spots. ,„..., ■ i .i 



Habitat.— Coroma,udtil coast of India. The example described, a male, 2<i inches in length, was m 



the Madras Museum. 



' Descent of Man," p. 331. 



