4. CYCLODEHMA.. — 5. KMYDA. 207 



a. Ad., shell. Zambezi. Dr. Liviiig'tone [P.]. (Typo of 



Aspidocheli/8 livinystonii. ) 



b. Skull, hyoid, k foot. Zambezi. Sir J. Kirk [P.]. 



(From the first Livingstone Expedition.) 



2. Cycloderma aubryi. 



Cryptopus aubryi, A. Bum. Rev. et Mag. de Zool. viii. p. 374, pi. xx. 



(18-30). 

 Ileptathyra aubryi, Cope, Proc. Ac. Philad. 1859, p. 294; Gray, 



^uppl. Cat. Sh. llept. i. p. 93 (1870). 

 Cycloderma aubryi, A. Dam. Arch. Mus. x. p. 100 (1800) ; Peters, 



Mon. Berl. Ac. 1870, p. 117, pi. — . 

 Heptathyra freuata, part., Gray, Proc. Zool. Soc. 1864, p. 93, figs. 



Differs from the preceding in the broader interorbital region, 

 which measures at least two tliirds the diameter of the orbit ; and 

 in the larger plastral callosities, especially the cntoplastral, which, 

 instead of being by far the smallest of all, is the largest next to the 

 hyo-hypoplastral and subcircular in shape ; hyo-hypoplastral callo- 

 sities in contact on the median line, lirown above ; young orange, 

 with a few black spots and a black vertebral line on the body, and 

 three black streaks along the head and neck. 



Length of dorsal disk 45 centim. 



Gaboon and Ogowai. 



a. Ad., stftll. Gaboon. M. Du Cliaillu [0.]. 



6. Ad., shell. Gaboon. M. Du Chaillu [O.J. 



c. Ad., skel., incomplete. Gaboon. IM. Du Chaillu [C.J. 



5. EMYDA. 



Trionyx, part., Geoffr. Ann. Mus. xiv. p. 1 (1809) ; ScMveu/g. Prodr. 



p. 18 (1814) ; Fitzhuj. Sijst. Ecpt. p. 7 (1820). 

 Trionyx, Wa(/l. Syst. Amph. p. 134 (1830). 

 Emyda, Gray, Syn. Rept. p. 49 (1831), and Cat. Tort. p. 46 (1844), 



and Sh. Rept. i. p. 03 (1855); Strauch, Chelon, Stud. p. 50 



(1862) ; Gunth. Rept. Brit. hid. p. 44 (1864) ; Gray, Suppl. Cat. 



Sh. Rept. i. p. 117 (1870), and Proc. Zool. Soc. 1873, p. 71. 

 Cryptopus, part., Bum. ^- Blhr. ii. p. 499 (1835). 

 Po'tamochelys, part., Gray, Proc. Zool. Soc. 1864, p. 85, and Stippl. 



Cat. Sh. Rept. p. 104, and Ann. ^ May. N. H. (4) x. p. 338 



(1872). 



Nuchal notched at each outer end, which underlies the first 

 costal plate ; dorsal shield large, with a series of bony plates in the 

 posterior cutaneous border and a proenuchal marginal bony plate ; 

 neural plates well developed, seven or eight in number, forming a 

 continuous series ; eighth pair of costals large in the adult, and, 

 like the penultimate, forming a median suture. Plastron with a 

 cutaneous femoral valve, under which the hind limb may be con- 

 cealed : hyoplastron coossitied with hypoplastron ; seven plastral 

 callosities (in the adult). Bony choanse between the orbits ; jaws 

 strong ; postorbital arch moderate, much narrower than the diameter 



