1864. ] DR. J. E. GRAY ON THE CHELYDID2. 133 
2. STERNOTHERUS DERBIANUS, Gray, /. c. 52, t. 22; P.Z.S. 
1863, p. 194. 
Pentonyx gabonensis, A. Dum. Arch. d. Mus. x. p. 164. 
** Crown with oblong shields, and small scales behind over the 
tympanum. Notoa. 
3. STERNOTHZRUS SUBNIGER, Gray, J. c. 52; P. Z. S. 1863, 
p- 195. Var. Ann. & Mag. N. H. 1863, xii. 405. 
S. castaneus, Dum. et Bib. Erp. Gén. t. 20. f. 1. 
*** Crown with three shields. Head elongate. 
4. STERNOTHERUS NIGER, Gray, J. c.51; P. Z.S. 1863, p. 196. 
Hab. Madagascar. 
8. PeLomepvusa, Gray, Cat. Shield Rept. 52. 
Lobes of sternum solid, immoveable. 
Had. Africa. 
* Pectoral shields small, short, triangular ; humeral large ; occipital 
with small shields. Pentonyx. 
1, PELOMEDUSA GEHAFIA, Gray, J. c. 53. 
** Pectoral and humeral shields equal, oblong, four-sided ; occipital 
largely shielded. Pelomedusa. 
2. PELOMEDUSA SUBRUFA, Gray, /. c. 53. 
3. PeELomEpusA NIGRA, Gray, Ann. & Mag. N. H. 1863, xii. 99. 
Pentonyx du cap, A. Duméril, Arch. du Mus. xiii. t. . f. 3. 
b. Head swollen. Skull very solid. Zygomatie arch much dilated 
posteriorly, so as to cover the temporal muscles with a bony 
case to the occiput. Alveolar surface of the jaws wide, callous, 
with several ridges. Claws 5—4. America. Chelonoid 
Chelydride. 
9. Popocnemis, Gray, Cat. Shield Rept. 61. 
Head subdepressed. Nose with a central groove. Temporal 
muscle partially covered with skin. Skull figured and described in 
Owen’s Cat. Osteol. Mus. Col. Surg. p. 203, no. 1056. 
* Alveolar surface of the upper jaw with three ridges: the hinder 
broad, low, margining the edge of the inner nos‘rils ; the two 
Sront sharp-edged, diverging to the end of the maxillary edge ; 
the first one short. Head broad, short. Podocnemis. 
1. Popocnemts ExPANSA, Wagler, N. Syst. Amph. t. 4; Gray, 
Cat. Shield Rept. 61, t. 27 (shell), t. 37. f. 1 (skull). 
