246 TRIONYCHIDiE. 



nuchal border of dorsal disk -without 



conical tubercles ; a light black-edged 



streak on each side of the head, uniting 



with its fellow into a large triangular 



marking extending from between the 



eyes to the end of the proboscis .... 12. emoryi, p. 258. 

 Snout a little longer than the diameter 



of the orbit ; nuchal border of dorsal 



disk with conical spine-like tubercles ; 



light head-streaks uniting on the 



snout, in front of the orbits 13. ferox, p. 259, 



Snout a little longer than the diameter of 



the orbit ; nuchal border of dorsal disk 



with conical spine-like tubercles; light 



head-streaks uniting on the end of the 



snout, at the base of the proboscis . . 14. spinifer, p. 25y. 

 Snout very narrow and pointed ; nuchal 



border of dorsal disk without conical 



tubercles 15. muticus, p. 2G0. 



1. Trionyx subplanus. 



Triouyx subplanus, Geoffr. Ann. Mus. xiv. p. 11, pi. v. fig. 2 (1809) ; 



Gray, III. Ind. Zool. i. pi. Ixxix. (1832) ; Giinth. Rept. Brit. Ind. 



p. 49 (18G4) ; Strauch, Verth. Schiklkr. p. 130 (18G5). 

 Gymnopus subplanus, Bum. S; Bibr. ii. p. 49G (1835). 

 Dogania subplaua, Gray, Cat. Tort. p. 49 (1844), and Sh. Rept. i. 



p. 69, pi. xxxiii. (18oo), and Proc. Zool. Soc. 1862, p. 265, and 



Suppl. Cat. Sh. Rept. i. p. 106 (1870), and Proc. Zool. Soc. 1873, 



p. 57, fig. 

 Trionyx frenatus, Gray, Cat. Sh. Rept. i. p. 67. 

 Dogania giiutlieri, Gray, Proc. Zool. Soc. 1862, p. 265, and Suppl. 



Cat. Sh. Rept. i. p. 107, and Proc. Zool. Soc. 1873, p. 58. 

 Trionyx giintheri, Giinth. Rept. Brit. Ind. p. 49, pi. vi. fig. A. 

 Potamochelys ? frenatus, Gray, Proc. Zool. Soc. 1864, p. S7. 

 Sarbieria freuata, Gray, Proc. Zool. Soc. 1869, p. 220, and Suppil. Cat. 



Sh. Rept. i. p. 100. 

 Platypeltis ferox, part., Gray, Proc. Zool. Soc. 1873, p. 58. 

 Triouyx ? dilhvyuii, Gray, Ann. Sf Mag. N. H. (4) xi. p. 306 (1873). 



Carapace very flat ; costal plates eight pairs, the last well deve- 

 loped and separated by the last neural plate ; a single neural be- 

 tween the first pair of costals ; these plates very finely granulate and 

 vermiculate ; a large fontanelle, till late in life, between the nuchal 

 and dorsal plates. Epiplastra narrowly separated from each other 

 in front of the entoplastron, which forms an obtuse or a right angle ; 

 plastral rugosities scarcely developed, on the hyo- and lijpoplastra 

 and on the xiphiplastra. Dorsal skin of young with interrupted 

 longitudinal ridges. Head very large ; snout (on the skull) about 

 as long as the diameter of the orbit, which is more than double the 

 interorbital width : postorbital arch extremely narrow, forming a 



