
638 The American Naturaiist. [July, 
which in the structure of carapace and plastron were very much 
like Carettochelys. On the other hand, there seem to be connec- 
tions through Anostira with the groups of Cryptodira named 
above. These affinities are shown in the shape of the skull and 
plastron, and the peculiar number of peripherals. Until the cer- 
vicals and pelves are known, I think it is impossible to determine 
the correct systematic position of the Carettochelyide. The most 
probable view seems to be this: The Carettochelyida came from 
a group of tortoises related to the stock from which Staurotypide 
and Cinosternide developed. It is probable that the Caretto- 
chelyide are very close to the ancestors of the Trionychia, of 
which they are only survivals. For the ancestors of the Triony- 
chia we have to look in the Jurassic and Lower Cretaceous ; for 
I have shown in another paper that the Trionychia of the Upper 
Cretaceous (Laramie) are typical forms, in which the peripheralia 
had been already entirely reduced. I have little doubt that these 
started from the Amphichelydia. 
There are some points which could be made out by examina- 
tion of the unique type specimen of Carettochelys; the entire 
structure of the skull, for instance, the condition of the first dor- 
sal, which is probably preserved. It would be very important to 
know whether the premaxillary is small and single, as in the 
Trionychia, or whether it is developed, as in the Staurotypida, for 
instance. It would be interesting to know whether the anterior 
part of the centrum of the first dorsal vertebra is modified as in 
the Trionychidz or not. 
I can only hope that new specimens will be collected soon in 
New Guinea. They doubtless exist there in great numbers, 
` and I think the time will not be very far away when we will 
know the whole anatomy of this most interesting tortoise. 
Clark University, Worcester, Mass., April 5th, 1891. 
AUTHORITIES CITED. 
1. RAMSAY, E. P.—On a New Genus and Species of Fresh-Water Tortoise, 
from the Fly River, New Guinea. Proc. Linn. Soc., New South Wales, Second 
Series, Vol. I., Part I., May 25th, 1886, pp. 1 58-162, Pls. r11.—vI. 






