CHELONID^. 



27 



there is a considerable probability that the one family is the descen- 

 dant of the other. Both the nature of the roof over the temporal 

 fossa and the presence of the intergular shield in some CJielonidce 

 appear to be archaic features ; the former, at least, being found to 

 a greater or less extent in the Acichelyidce. The open tympanic 

 ring may likewise be regarded as an archaic feature \ 



Genus CHELONE, Brongniart 2 . 



Including : — Cimo\lio]ehelys, Owen 3 . 

 Allopleuron, Baur *. 



Skull (fig. 7) comparatively long, narrow, with the orbits lateral, 

 the nares more or less nearly vertical, and usually no occipital 



Fig. 7 



Ckelone imhricata. — Palatal and frontal aspects of the cranium. Eeduced. 

 (From Boulenger's ' Catalogue of Chelonians.') 



1 See Baur, Ann, Mag. Nat. Hist. ser. 6, vol. iii. p. 60 (1889). 



2 Bull. Soc. Philom. vol. ii. p. 89 (1800).— Amended. 



3 Eep. Brit. Assoc: for 1841, p. 176 (1842). 



4 Science, vol. xi. p. 144 (1888). 



