HINGED TORTOISES. 
6 3 
the shell can be completely closed. This hinge runs between the fourth and fifth 
costal bones and the seventh and eighth marginals of the shell. The skull agrees 
with that of the preceding genus, in the absence of a median ridge on the front of 
the palate, while the neural bones of the carapace are hexagonal and short-sided 
behind, and the caudal shield is undivided. The costal bones of the carapace 
differ, however, from those of the tortoises described above, in being of nearly 
equal width throughout, instead of alternately narrow at one end and broad at 
the other. Of the three species of the genus, the clentated hinged tortoise (Cinixys 
erosa), from Guinea and the Gabun, is characterised by the front and hind margins 
DENTATED HINGED TORTOISES (| liat. size). 
of the carapace being everted and strongly dentated; by the absence of a nuchal 
shield, the projection of the extremity of the plastron in front of the carapace, and 
the sloping contour of the hinder extremity of the latter. The length of the shell 
is 9 inches; its general colour above being dark brown, with lighter centres to the 
shields, and the lower sides of the costal shields yellowish; while on the plastron 
the shields have dark brown centres and yellowish margins. In the nearly allied 
Home’s hinged tortoise ( 0 . homeana), from the same regions, there is a nuchal 
shield, the extremity of the plastron does not project in advance of carapace, and 
the hinder extremity of the latter descends vertically. On the other hand, Bell’s 
hinged tortoise (0. belliana), which ranges right across tropical Africa, the margins 
of the carapace are neither everted nor serrated; a nuchal shield being present on 
the front of the carapace. In length the latter does not exceed 7| inches. 
