250 TRIONYCHID^. 



Trionyx gangeticus, part., Gray, Cat. Sh. liept. i. p. 66 (1855), and 



Suppl. p. 97 (1870) ; T/teoh. Proc. As. Soc. Beiig. 1875, p. 171, and 



Cat. Rept. Brit. Ind. p. 28 (1876). 

 sewaare, Gray, Ann. Sf Mar/. N. II. (4) x. p. 330 (1872), aixd 



Proc. Zool. Soc. 1873, p. 50, figs.; Theoh. Proc. As. Soc. Benff. 



1875, p. 172, and Cat. liept. Brit. Ind. p. 29. 

 bellii, Gray, II. cc. pp. 337 & 51. 



Nilssonia forniosa, part., Graij, Proc. Zool. Soc. 1873, pp. 45 & 46, 



figs. 

 Trionyx buchanani, Theob. Proc. As. Soc. Benf/. 1874, p. 78._ 

 ? Trion^-x nigricaiis,'_^H(Zers. Ajm. ^- May. N. II. (4) xvi. p. 284 



(1875). 



Costal plates eight pairs, the last well developed and in contact 

 throughout on the median line ; two neurals between the first pair 

 of costals : plates coarsely pitted and vermiculate. Epiplastra nar- 

 rowly separated from each other in front of the entoplastron, which 

 forms an obtuse or a straight angle ; plastral callosities very large, 

 hyo-hypoplastral, xiphiplastral, and in old specimens cntroplastral. 

 Dorsal skin of young with longitudinal ridges of small tubercles. 

 Head moderate ; snout (on the skuU) a little longer than the dia- 

 meter of the orbit ; interorbital region, in the adult, as broad as 

 the nasal fossa ; postorbital arch somewhat more than half the dia- 

 meter of the orbit ii. the adult ; mandible without strongly raised 

 inner edge or longitudinal symphysial ridge ; the diameter of the 

 mandible at the symphysis exceeds the diameter of the orbit. Olive- 

 brown above and beneath ; head, neck, limbs, and border of shell 

 light-doited ; head with large yellow spots, viz. across the snout, 

 behind the orbit, at the angle of the mouth, on the tympanic region 

 and on the chin ; these spots become indistinct in the adult, the 

 head of which is more or less closely spotted or vermiculated with 

 black ; dorsal disk in the young Avith dark marblings and four or 

 six very large ocelli. 



Length of dorsal disk 40 centim. 



Ganges. 



a. Ad., skel. Calcutta. 



h-c, d-f. I'g., spir. Ganges. 



(J ¥<>•.', skull. Ganges. W. Theobald, Esq. [P.]. 



h. H|r., skull & shell. Bengal. W. Theobald, Esq. [P.]. 



i. Yg., skull & carapace. India. Dr. Falconer [P.]. 



h. Yg., spir. ? 



I. Ad., skull. ? 



5. Trionjrx formosus. 



Trionyx formosus. Gray, Proc. Zool. Soc. 1869, p. 217, pi. xv. fig. 1, 

 and Suppl. Cat. Sh. liepf. i. p. 99 (1870) ; Theoh. Cat. liejit. Brit. 

 Ind. p. 31 (1876). 



jeudi, part., Graij, Suppl, p. 98. 



pegueusis, Gi-ay, Suppl. p. 09 ; Theoh. Proc. As. Soc. Beng. 1875, 



p. 176, and Cut. Bept. Brit. Ind. p. 31 ; Anders. Zool. lies 

 Ynn7ian, p. 786, pis. Ixx.-lxxiii. (1879). 

 Nilssonia formosa, Gray, Ann. ^- May. N. H. (4) x. p. 333 (1872) 



