228 CHELYDlDiE. 



small : posterior notch of plastron feeble. Head mucli flattened, 

 covered with nndividod 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, crescontic 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 interiorly, 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 lo centim. 



Guianas, Brazil, North-eastern Peni. 



a. 2 , spir. British Guiana. Sir E,. Schomburgk [P.]. 



h. 2 , spir. Demerara Falls. 



c,d. (5' 2 , shells. Demevara. 



c. Ilgr., spir. Surinam. 



f. 2 , spir. Guiana. 



(J. c?, stfEd. Ilio Xegi-o, Brazil. H. W. Bates, Esq. [0.]. 



h. 2, dry. Santa Cruz, Iluallaga 



Kiver, N.E. Peru. 



i. Hgr., skel. ? 



7. EMYDURA. 



Hydraspis, part., Gray, Spi. Eept. p. 39 (1831). 



Platemys, part., Bum. Sf Bihr. ii. p. 404: (1835) ; StrmicJi, Chelon. 



Stud. p. 45 (18Gl^). 

 Emvdura, Bonap. Arch. f. Nat. 1838, i. p. 140. 

 Cbe'lvmys, Gray, Cat. fort. p. A± (1844), and Sh. Ilept. i. p. 57 



(185.5), and Suppl p. 75 (1870), and App. p. 20 (187i^). 

 Elseva, part., Grap, Ann. 4* Ma(/. N. II. (4) xx. p. 44 (18G7), and 



Suppl, Cat. >Sh. lii'pt. i. p. 70, and App. p. '22. 

 Euclielymys, Gray, Ann. ^- Mag. N. II. (5) viii. p. 118 (1871), and 



App'. ik'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 filth and sixth costal plates. 

 A supraoccipital arch ; parietal bones much expanded, forming a 

 roof; jaws very strong, without alveolar ridges ; the Avidth 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 s]iccies of this and the following genus differ from all other 

 Chelydida"! in not having the lirst vertebral shield larger than the 

 second. The limbs are similar to those of I{i/drasj>is. 



