1864. ] DR. J. E. GRAY ON THE TRIONYCHID2. 87 
Face moderately long, subconical, rather convex ; forehead and 
crown flat (length from back of orbit to nose and to occiput the 
same), longer than in P. stedlatus ; nostrils large, rather close, with a 
very small lobe on the inner side of each. 
The neck of the young specimens with a dark-edged pale streak on 
each side, which is bent down towards the throat behind; head 
brown, black-speckled, with a narrow line across the forehead on the 
front edge of the eye. 
3. PorTAMOCHELYS” FRENATUS. 
Trionyx frenatus, Gray, Cat. Shield Rept. 67. 
Hab. Singapore (Wallace). 
4. POTAMOCHELYS? TUBERCULATUS. 
Trionyx tuberculatus, Cantor; Gray, P. Z. 8. 1861, p. 42. 
Hab. Chusan. 
5. PoTAMOCHELYS? MICROCEPHALUS, 0.8. 
Olive-brown. The hinder part of the disk nearly smooth, without 
any rows of tubercles. The first vertebral bones transverse, short, 
rugose, with two circular pits behind, between it and the second 
vertebral plate (probably disappearing in the adult); sternal callo- 
sities four, evenly rugose ; head small, slender, rather elongate ; nose 
slender, conical, tapering. 
Hab. Sarawak (Wallace). 
This species differs from all the other Mud-Tortoises from Asia in 
the small size, slender and tapering form of the head. It is evidently 
a young specimen, from the extent of the ribs, which are still free, 
and the separate state of the bones of the head ; but the dorsal bony 
disk and the sternal callosities are well developed. 
This Tortoise will probably be found to form a genus by itself, 
when the adult animal has been examined. 
See also— 
‘1. Trionyx maackii, Brandt, Bull. Acad. St. Petersb. xvi. 110, 
1857; Institute, xxvi. no. 1288, p. 298; Arch. f. Nat. 1858, 
p- 63. 
Hab. N. China: Amoor River. 
2. Trionyx schlegelii, Brandt, 1. e. 1857. 
T. stellata, sive javanica, var. japonica, Schlegel, Fauna Japon. 
t. 8 (animal), t. 5. f. 7 (head). 
Hab. Japan. 
** Palate flat, with a broad shallow groove of equal width in front 
of the large posterior internal nostrils, which have two short 
deep grooves. behind them. 
TYRSE. 
Sternal callosities four. Nose elongate, conical, shelving. Fore- 
