1 7. TRYQOX. 477 



Tail without any told, Dnc-tliii'd shorter than the disk, extremely 

 thin behind the 8])ine. Disk rounded, ovate, rather longer than 

 broad. Eyes very small. Ui)i)er parts rough. There are two 

 larger thorns with broad base on the root of the tail. Disk with un- 

 dulating markings, posteriorly crossing the fin-rays. (J/. ^" T.) 



British Guiana. 



bb. Tail with an inferior or superior cutaneous fold. 



10. Trygon thalassia. 



Pastinaca, Bellon. De Aquat. p. 94 ; Gcsner, De Aquat. p. 77 ; Wil- 



luyhhy, p. 67, tab. D 5. fig. .",. 

 Trygou thalassia, Columna, Phi/sobatos, p. 105, tab. 28. 

 Raja gesneri, Cuv. Rigne Anim. 

 Trygon thalassia, Midi. S)- Ilcnle, pp. IGl, 197. 

 Pastinaca acanthm-a, Gronov. Sijst. ed. Grai/, p. 12. 



Tail with a cutaneous fold along the lower side, the depth of the 

 fold being less than that of the tail. Tail much longer than the 

 body (but generally mutilated in old examples). Anterior profile ob- 

 tuse. Large conical thorns, in greater or less number, inserted on a 

 round radiated base, are distributed along the midcUe of the back, on 

 the scapulary and other regions, and especially on the tail, where 

 they occupy the sides as well as the upper surface ; even the cutaneous 

 fold is covered with smaller stellate ossifications. 



Adriatic and probably Atlantic. — A similar species exists in the 

 Pacific, with a deeper caudal fin ; but this is known to me from a 

 tail only. 



a. Large example, stuffed : body 4 feet long. 



b. Large male. Madeira. Presented by J. Y. Johnson, Esq. 

 c~f. Tails of very large examples. 



g-h. Jaws of large examples. 



11. Trygon brucco. 



Bonap. Faun. Ital. Peso. ; Duvt^ril, Elasmohr. p. G02. 



Tail with a distinct cutaneoua fold below, nearly twice as long as the 

 disk. The anterior profile of the disk is scarcely interrupted by a pro- 

 jection of the snout, forming a nearly continuous arch. Body smooth. 

 Brownish above, white below. 



Mediterranean. 



«. Skin of an adult example, without tail. From Mr. Yarrcll's Col- 

 lection. 



12. Trygon violacea. 

 Bonaparte, Faun. Ital. I'esc. ; 3Iiill. l^ Ilenle, pp. 102, 20O. 

 Tail with a distinct cutaneous fold below, more than twice as long 

 as the disk. The anterior profile of the disk is a continuous arch, 

 not interrupted by the projection of the snout. A series of thorns in 

 the median line of the back to the caudal spine, and some others in 

 the scapulary region. Older individuals with scattered a-*peritieson 



