Dr. J. E. Gray on the Mud- Tortoises of India. 333 



Esq. (68. 2. 12. 15). It is known from the skulls of Trionyx, 

 which it greatly resembles, by the narrowness of the groove 

 in front of the palate to the internal nostrils ; in Trionyx 

 gangeticusj T. Jeudii^ and in T. Leithii this groove is broad 

 and shallow, and nearly of uniform width. 



1. Nilssonia formosa. 

 Young only known. Callosities not developed. 

 Back of the crown with a broad transverse pale band. 



Trionyx fonnosiis, Gray, P. Z. S. 1869, p. 217, tab. 15. fig. 1 ; Suppl. 

 Cat. Shield Eept. p. 99. 



Hub. Pegu (B.M.). 



The skull of the young is shorter and broader than those of 

 the adults. I believe this arises only from difference of age. 



Teionyx. 

 The dorsal disk in the young animals is generally marked 

 with three pairs of black spots, which have concentric pale 

 rings within. These spots often last in a more or less perfect 

 degree throughout the life of the animal ; sometimes the anterior 

 and sometimes the posterior pair, and rarely a spot on one side 

 of these pairs, are deficient. The crown of the head of the 

 young specimens is generally marked with spots of various 

 colours, which become more and more indistinct as the animal 

 grows. I believe that these spots are characteristic of the 

 species ; and sometimes whole series of species have character- 

 istic spots — that is to say, on the sides of the crown and face. 



t Crotun of head olive, with radiating black lilies behind. 

 1. Trionyx gang eticus. (Dekoolee.) 

 Skull short, broad ; nose suddenly bent down, with a rounded 

 outline ; eyes within a very short distance of the cavity of the 

 nostrils, which is not as long as the diameter of the orbit ; al- 

 veolar surface of the lower jaw deeply concave, with a very 

 slight, indistinct, central longitudinal ridge. 



^'■Dekoolee " Hardwicke, icon. iued. 



Trionyx du Gauge, Cuvier, Oss. Foss. v. pt. 2, p. 187, tab. ii. figs. 5-8 



(skull). 

 Trionyx qangeiicm, "Duvaucel," Cuvier, Regne Anini. vol. ii. p. IG ; 



Gray, Cat. Shield Rept. B. M.p. 66, Suppl. p. 97 (skull only). 

 Gymnopus Duvaucelii, Dumeril & Bibron, Erpet. Gen. vol. ii. p. 47. 

 Aspidonectes gnnyeticus, Wagler, Amphib. Taf. 2, figs. 13-22 (copied 



from Cuvier). 

 Trionyx javanicus, Gray, Cat. Shield Rept. p. 67 (not synonyma). 

 Potamochelys stcllata, Gray, P. Z. S. 1864, p. 85; Suppl. Cat. Shield 



Rept. B. M. p. 104 (animal only, not skull). 



Var.? The black lines irregular. 

 ^'Jaanh" Hardwicke, icon. ined. 



