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486 — The American Naturalist. [May, 
The Genera of the Cheloniidze.—Boulenger, in his Catalogue 
of Tortoises, admits only two genera of Cheloniide—Chelone and 
Thalassochelys. His genus Chelone includes Caretta or Eretmochelys, 
Euchelys and Onychochelys. His Thalassochelys includes Lepido- 
chelys, Colpochelys, Cephalochelys and Eremonia. 
I have examined a great number of skulls and skeletons of Chelonii- 
dæ in different museums, and have reached the following conclusions, 
which partially at least have been published before: 
1. Chelonia Brogn., 1799. Jour. des Sciences des Lettres et des A rts, 
par A. L: Millin. Vol. V., 6, 1799. 
Orbit formed by: Srefrontal, frontal, postfronto-orbital, jugal, 
maxillary. 
Maxillaries separated by vomer, 
Descending processes of prefrontals in connection with palatines. 
Number of peripheralia, 11 ; No. ro without connection with rib. 
Type: Chelonia mydas L. 
2. Caretta Ritgen, 1828. Eretmochelys, Fitz 
Orbit formed by: prefrontal, frontal, postfronto-orbital, jugal, 
maxillary. 
Maxillaries separated by vomer. 
gence processes of prefrontals without connection with pala- 
cas of peripheralia, Ir; peripherale 9 without connection 
with ri 
Type: Caretta imbricata L. 
3- Thalassochelys, Fitzinger, 1835. 
Orbit formed by: prefrontal, oo jugal, maxillary. 
Maxillaries in contact, not separated by vomer, 
Descending processes of prefrontals in connection with palatines. 
- Number of peripheralia, 11; ; peripherale 9 without connection 
with rib. 
Type: Zh. caretta L. 
4. Lepidochelys (Fitzinger) Gray, Colpochelys Garman. 
Orbit formed by: prefrontal, postfronto-orbital, jugal, maxillary. 
Maxillaries separated by vomer 
Descending processes of pieteahitadd without connection with pala- 
tines, 
Thalassochelys, 
Type: Z. olivacea tcaci 
Number of peripherlia, 1r or more; connection with ribs as in 
y 
