228 CHELYDID&. 
small; posterior notch of plastron feeble. Head much flattened, 
covered with undivided skin above; snout strongly projecting ; 
parietal bones much expanded, their width much greater than the 
diameter of the orbit; mental barbels very small. Upper surface 
of neck with round or conical tubercles, those on the sides largest 
and erect. Limbs shortly webbed, covered with large scales, those 
on the upper arm and thigh being the largest; a much developed, 
compressed, crescentic process on the inner side of the leg, formed 
by two or three very large tubercles. Carapace chestnut-brown 
above, with a large black blotch on each side on the costals ; mar- 
ginals yellow inferiorly, with triangular black spots; plastron 
blackish brown, bordered with yellow; a blackish-brown band on 
the bridge; head yellowish above, dark brown or black on the sides 
and below. 
Length of shell 15 centim. 
Guianas, Brazil, North-eastern Peru. 
a. 9, spir. British Guiana. Sir R. Schomburgk [P.]. 
b. 2, spir. Demerara Falls. 
c,d. S @, shells. Demerara. 
e. Hgr., spix. Surinam. 
F-. Q; spir. Guiana. 
g. 3, stfid. Rio Negro, Brazil. H. W. Bates, Esq. [C.]. 
h, 2, dry. Santa Cruz, Huallaga 
River, N.E. Peru. 
p 
7. Her., skel. 
7. EMYDURA. 
Hydraspis, part., Gray, Syn. Rept. p. 89 (1831). 
Platemys, part., Dum. § Bibr. ii. p. 404 (1835); Strauch, Chelon. 
Stud. p. 45 (1862). 
Emydura, Bonap. Arch. f. Nat. 1838, i. p. 140, 
Chelymys, Gray, Cat. Tort. p. 42 (1844), and Sh. Rept. i. p. 57 
(1855), and Suppl. p. 75 (1870), and App. p. 20 (1872). 
Elseya, part., Gray, Ann. § May. N. H. (4) xx. p. 44 (1867), and 
Suppl. Cat. Sh. Rept. i. p. 76, and App. p. 22. 
Euchelymys, Gray, Ann. § Mag. N. H. (5) viii. p. 118 (1871), and 
App. p. 21. 
Neural plates absent; nuchal shield present or absent. Plastron 
large, with very strong axillary and short inguinal buttresses, the 
latter reaching the fifth or between the fifth and sixth costal plates. 
A supraoccipital arch; parictal bones much expanded, forming a 
roof; jaws very strong, without alveolar ridges ; the width of the 
lower jaw at the symphysis equals at least the diameter of the 
orbit. Chin with or without dermal appendages. Digits entirely 
webbed. 
Australia and New Guinea. 
The species of this and the following genus differ from all other 
Chelydide in not having the first vertebral shield larger than the 
second, ‘The limbs are similar to those of Hydraspis, 
