1873.] DR. J. E. GRAY ON THE TRIONYCHID.E. 71 



Cyclanosteus (Cyclanorbis) petersii, Gray, P. Z. S. 1852, p. 135 ; 

 Ann. & Mag. N. H. 1855, xv. p. 69. 



Cyclanosteus petersii, Gray, Cat. Sh. Rept. p. 64, t. 29 (shield) ; 

 P. Z. S. 1860, p. 315. 



Cyclanosteus seneyalensis, Gray, P. Z. S. 1864, p. 95, figs. 16-18 

 (skull) ; P. Z. S. 1865, p. 427 ; Suppl. Cat. Sh. Rept. p. 1 12, fio-. 37 

 (skull), fig. 38 (sternum). s 



Hub. Rivers of Western Africa ; Gambia, Senegal. 



The different specimens of this species have the sternal callosities 

 differing in shape and proportion as regards each other. 



Thus the specimen figured as C. petersii, Cat. Sh. Rept. t. 29 

 (the skeleton in the Museum), has the central odd callosity half the 

 width of the pair of bones before it, and the hinder pair of callosities 

 small and roundish. 



A second specimen in the Museum has the central odd callosity 

 more than two thirds the width of the pair* of callosities before it; 

 and the hinder pair of callosities is ovate, nearly the whole length of 

 the bones on which they are situated, and are diverging from each 

 other. This specimen has an additional callosity on the right side of 

 the odd callosity. There is another specimen in the Museum which 

 has this additional callosity on each side of the central callosity (see 

 Suppl. Cat. Sh. Rept. p. 113, fig. 38). 



There is a third specimen, which differs in the odd central 

 callosity being transverse and subtriangular, and nearly as broad as 

 the pair of bones before it (see Suppl. Cat. Sh. Rept. p. 113, 

 fig. 38a, where these callosities are figured). In this specimen the 

 hinder callosities are entirely wanting or, rather, undeveloped. 



** 



Fhe dorsal disk with a regular series of marginal bones on the 

 hinder lateral edge, and with a single marginal bone in front, 

 all callous and rugose externally. — India. 



Emyda. 



Emyda, Gray, Suppl. Cat. Sh. Rept. p. 117, and fig. 24, p. 105 

 (skull, as Pelochelys stellata); Ann. & Mag. Nat. Hist. 1872,x.p.340. 



Lower jaw with a narrow edge, and shelving internally in front, 

 with a wide concave alveolar edge on the sides. 



The dorsal disk with a central bone, callous on the outer side in 

 the middle of the front margin, rather large and separate from but 

 received into a notch in the front edge of the odd bone of the dorsal 

 disk. A regular series of bones, which are callous externally on the 

 hinder lateral margin. Sternum with seven callosities— one pair 

 anterior, one pair lateral, and one pair posterior, and one single 

 central callosity, which is generally of a roundish form. 



1. Emyda punctata. 



Anal callosities oval, oblique, inner edge of each rounded. 



Testudo punctata, Lace'p. Qu. O. t. 171. 



Testudo scabra, Latr. Rept. i. p. 194. 



Testudo dura, 13. Hamilton, icon. ined. 



