REPTILIA. 
107 
t>f this s{i6cies from West Africa j he describes aind figures it^ refetrihg it to 
the siibgenu^ Notooy Proc. Zool. Soc. 1864, p. 296, pi. 23. 
Fam. Trionychid^. The following species are figured by 
Gunther : — 
Trionyx (Gray), pi. 6. fig. B; Tridnyx yuntheri (Gray), pi. 6. fig. A ; 
Chitra indica (Gray), pi. 6, fig. C. 
Dr. J. E. Gray has made a most valuable contribution to our 
kno\^ledge of the African and Asiatic species of this family, 
Proc. ZooL Soc. 1864, p. 76. After deferring to Agassizes re- 
searches on the American species, and giving an outline of the 
history t)f the genera established, he states that he concurs with 
Agassiz’s opinion, that great confidence is to be placed in cha- 
racters furnished by the general form of the skull, and in the 
position and extent of the choanse. The paper being accompanied 
with a series of Woodcuts of the skulls examined, a glance at 
them will at once reveal striking differences between them ; but - 
it is another question whether those differences are of generic 
value. The best way to determine whether an osteological cha- 
racter is of generic value, is to find whether it is constantly 
accompanied by an external one, and vice versd ^ another way 
of determining its value, is to look whether it occurs in a whole 
series of species. Now, it would appear to the Recorder that 
the material at present available for examination has proved to ' 
be too little to enable one to do this. Dr. Gray considering (with 
one exception) every species the skull of which was examined 
by hiitt, as the type of a distinct gentis. The external similarity 
of these gehera is so great, that no othet charactef could be 
found to distinguish them, and consequently the author must 
leave it doubtful to which genera those species should be refer- 
red the skulls of which are unknown. 
The principal divisions are the same as those proposed by the 
author in his ^ Shield Reptiles,’ p. 63. 
A. The typical forms with the head moderate, face conical, 
eyes lateral” [Ti'ionycMfid) are subdivided thus - 
a. Lower jaW (of adult) with a broad, fiat alveolar disk ; palate with a 
deep, wide concavity in front of the inner nostrils. To this group 
belong:— 
TriotiyXy Gray, p. 81 ; type Trionyx gangeticus (Cuv.). 
RafetuSy Gray, p. 81 ; type Testudo mphratica (Baud.). 
Daganitty Gray, p. 82 ; type Dogania snhplana (Gray), with Dopania 
gilntheri (Gray) ; skulls of both species examined, that of the first 
species figured. 
AspiluSy Gray, p. 83 ; t|jq)e Triohyx cariwiferus (Grky) j the skull of 
this species is figured; Aspihvs (?) punctidatu^ (Gmy) and Ti'ionyx 
ornatuSy Gray, are referred to this genus with doubt. 
h. Lower jaw with a simple sharp shelving edge in front, and a flat 
shelving alveoltir disk on the hinder half. 
