Qe, TRIONYCHID ZA. 
Cycloderma senegalense, 4. Dum, Arch. Mus. x. p. 168 (1860). 
petersii, Strauch, Chelon. Stud. p. 56 (1862). 
Cyclanosteus senegalensis, Gray, Proc. Zool. Soc. 1864, p. 95, and 
1865, p. 422, figs., and Suppl. Cat. Sh. Rept. i. p. 112 (1870), and 
Proe. Zool. Soc. 1875, p. 70. 
Tetrathyra baikii, Gray, Proc. Zool. Soc. 1865, p. 324, fig., and 
Suppl. Cat. Sh. Rept. p. 110. 
Baikiea elegans, part., Gray, Proc. Zool, Soc, 1869, p. 222, and Suppl. 
Cat. Sh. Rept. p. 115. 
Carapace and plastral callosities rather finely granulate and ver- 
miculate ; two neural plates between the first pair of costals; at 
least nine plastral callosities in the adult, sometimes more, additional 
small plates being present on the sides of the epiplastra and between 
the latter and the hyoplastra; xiphiplastral plates usually the 
smallest ; the hyo-hypoplastral and epiplastral callosities developed 
before the others. Head moderate; snout short; orbit nearly 
equidistant from the nasal and temporal fossse ; interorbital space 
at least half the greatest diameter of the orbit in the adult; no 
protuberance at the symphysis of the mandible. Dorsal disk of 
young with longitudinal ridges of small tubercles. Olive above, 
uniform or with small dark spots on the dorsal disk; head with 
numerous small light spots; plastron yellowish, clouded with brown. 
Length of dorsal disk 35 centim. 
Senegambia to Upper Nile. 
a, Her., shell. Gambia. Earl of Derby [P.]. (Type 
of C. petersiz.) 
b. Her.,skel.,imperfect. | Gambia. Earl of Derby [P. ]. 
ec. Yg., spir. Senegal. 
d-f, g-m. Yg., spir. W. Africa. Dr. B. Baikie [C.]. 
n. Ad., stffd. W. Africa. Dr. B, Baikie [C. | 
o,p. Yg., stffd. W. Africa. Dr. B. Baikie [C.]. (Types 
of Tetrathyra bakit.) 
g. Hegr., shell. W. Africa. Dr. B. Baikie [C.]. 
r, 8, t. Ad., skulls, W. Africa. Dr. B. Baikie bert (Types 
of Baikiea elegans.) 
u,v, w. Her., skulls. W. Africa. Dr. B. Baikie [C. }. 
9 
x,y. Hgr., shells. —! 
2. Cyclanorbis elegans. 
Baikiea elegans, part., Gray, Proc. Zool. Soc. 1869, p. 222, pl. xv. 
f, 2, and Suppl. Cat. Sh. Rept. i. p. 115 (1870). 
This species, which is known from quite young specimens only, 
differs from the preceding in the presence of a strong knob on the 
inner surface of the symphysis of the mandible, in the larger dorsal 
dermal tubercles, and in the coloration. Dorsal and ventral disks 
dark brown, the former with very large irregular yellowish spots, 
the latter with small round spots of the same colour; head and 
chin with closely-set yellowish spots separated by a brown network. 
West Africa. 
a. Yg.,spir.; 6. Yg., stfid. W. Africa. - Dr. B. Baikie [C.]. 
(Types.) 
