6. CYCLANORBIS. 271 
the costals meeting on the median line and separating the neurals 
from each other; eighth pair of costals large. Plastron with a 
Skull of Cyclanorbis senegalensis, (From Gray, P. Z. 8. 1864.) 
cutaneous femoral valve, under which the hind limb may be con- 
cealed ; hyoplastron coossified with hypoplastron; nine or more 
plastral callosities in the adult, a pair being present in front of, and 
ossifying independently from, the epiplastrals. Bony choane 
between the orbits; jaws strong; postorbital arch moderate, nar- 
rower than the diameter of the orbit; posterior border of pterygoids 
with a median ascending process forming a suture with the opis- 
thotic. 
Tropical Africa. 
1. Cyclanorbis senegalensis. 
Cryptopus senegalensis, Dum. § Bibr. ii. p. 504 (1835), 
Emyda senegalensis, Gray, Cat. Tort. p. 47 (1844), and Sh. Rept. 
i. p. 64 (1855). 
Cyclanorbis petersii, Gray, Proc. Zool, Soc. 1852, p, 135. 
Cyclanosteus petersii, Gray, Proc. Zool, Soc, 1855, p. 201, and Cat. 
Sh. Rept. i. p. 64, pl. xxix, 
