igog.] N. Annandale : Report on the Batoidei. 19 



A. All the denticles with stellate bases. 



[a) Distance between the eyes less than half the length of the snout. 



Base of tail broad and flat . . . . T. microps- 



B. All or most of the dorsal denticles with round or polygonal bases. 

 {a) Dorsal denticles forming a regular wine-glass-shaped figure with 



well-defined borders. 



(a^) Distance between the eyes less than half the length of 



the snout . . . . . . T. bleekeri. 



(a-) Distance between the eyes more than half the length 



of the snout . . . . . . T. gerrardii. 



(b) Denticles not forming a regular figure on the back. 



(6') Dorsal denticles, if present , confined to the middle line. 

 Dorsal surface pink or red . . . . T. bennettii. 



{b'^) Dorsal denticles absent from the pelvic fins, flat and 

 rounded. Dorsal surface olive-brown with faint pale 

 spots scattered all over the disk T.alcockn,sp.nov. 

 {¥) A row of sharp spines running down the middle of 

 the back and the base of the tail. Dorsal surface 

 olive-brown, without spots . . T. jenkinsii, sp. nov. 

 (è^) Flat dorsal denticles irregularly interspersed with small 

 stellate ones on the body ; the pectoral fins covered 

 with small stellate denticles. Dorsal surface grey- 

 ish . . . . . . T. marginatus. 



(b^) Flat dorsal denticles irregularly interspersed with small 

 stellate ones, which are absent from the pectorals. 

 Dorsal surface of adult pale brown with darker mark- 

 ings; of young white with black spots T. uarnak. 

 {¥) No stellate denticles. Dorsal surface of adult dark 

 brown with a bold honeycomb pattern of dull yellow. 



T. favus, sp. nov. 

 II. Small species (adults less than 40 cm. across the disk, young not more 

 than 10 cm.). 



A. Distance between the eyes about one- third the length of the snout. 



Dorsal surface dark brown . . . . . . T. zugei. 



B. Distance between the eyes less than half the length of the snout. 



Dorsal surface pale brown . . . . T. imbricata. 



C. Distance between the eyes almost as great as the length of the snout. 



Dorsal surface grey with bluish spots . . . . T. kuhlii. 



The only species named in the key I have not seen is Trygon bennettii. Duméril 

 {Nat. Hist. Poissons, i, p. 596, 1865) records a specimen of this species measuring 43 

 cm. across the disk, while one of Henle and Müller ' s M^as rather larger { ' ' Plagiostomen, ' ' 

 p. 161). All the figures I have seen, however, look as though they represent young 



