Arte 
DERMATEMYDID&. 225 
crowded the humerals against the intergulars into the place of the supprest gulars. Then 
the pectorals and the abdominals have coalesct. 
In Anosteira apparently the plastral scutes were so delicate that they left no impressions 
of the sulci on the bones. ; 
Usually there are no striking modifications of the scutes of the carapace; but attention 
may be called to those of Xenochelys, and more especially to those of Anosteira. 
As regards the geological continuance of the family, we find the earliest form, Basilem ys, 
in the Judith River beds and three genera exist to-day. All together sixteen genera are here 
recognized, and these have the geological distribution presented in the accompanying table. 
. . . . p e D cé r 7 yx 1 ; 
Geological Distribution of the Genera of B I ee * has been described from the 
Dee Heald. Bruxellian of Belgium by Dr. Louis Dollo. 
> _ There can be no doubt that it is related to Anos- 
Formations. Genera. terra of America. The Bruxellian beds are equiv- 
alents of our Wind River deposits. Anostetra 
anglica has been described from the Lower Oli- 
| Pleistocene....... gocene of Hordwell, England. The character of 
———|— === = ~~ the sculpture and the straightness of the hypo- 
= — z 
IRECEN bese tearalsirr<ts Dermatemys, Staurotypus, Claudius. 
Pliocene......... : : : ‘ 
a el ___ xiphiplastral suture suggest a closer relationship 
a | with Pseudotrionyx than with Anosterra. Like 
; —|——_————_—_——_——— Anostetra, Pseudotrionyx probably had only 10 
| Oligocene. --| Xenochelys, Anosteira ? pairs of peripherals ; 
Pere ne eA crea naptemys, ePacudotrionys, We know nothing about the history of the 
Kallistira, Notomorpha, Alamos-| Dermatemydidz prior to the Upper Cretaceous. 
emys, Hoplochelys. Tretosternon Owen, of the Wealden, suggests 
We sbetcrerartous | Adects,, Homorophus, Zygoranima, strongly the genus Adocus; but the skull is said 
Agomphus, Compsemys, Basilemys. by Dollo (Peltochelys duchastel11, Bull. Mus. roy. 
Ci <a ss a a @hist. nat., Belgique, 111, 1884, p. 79) to have 
the temporal region protected by a bony roof. It is easy to conjecture that some form similar 
to Tretosternon was the Jurassic ancestor of the Dermatemydidz, which during the Upper 
Cretaceous times evolved into so many genera and species. 
As already stated, Pseudotrionyx of the Middle Eocene is evidently related to the Derma- 
temydide. It is believed to be related also to Carettochelys insculpta, a species living in the 
Fly River, New Guinea. Happily, our knowledge of this species has been increast by the 
description of a better specimen than either of those previously known. ‘This description is 
given by Mr. Edgar R. Waite in the Records of the Australian Museum, vi, 1905, pp. 110-118, 
and is illustrated by four plates and three text-hgures. Baur regarded this turtle as belonging 
among the Trionychidz, but as being closely akin to Pseudotrionyx and exhibiting connections 
with the Dermatemydida. Waite shows that the turtle is a true Cryptodiran nearest to the 
Dermatemydidz, but also as connecting the Cryptodira with the Trionychide. The animal 
is certainly a Cryptodire, but not a dermatemyd. It belongs to a family near the Derma- 
temydide. Probably Pseudotrionyx belonged to the same family; and a comparison of the 
figures of the shell with those of Dollo’s Peltochelys duchastellit (Bull. Mus. roy. Hist. Nat., 
Belgique, 111, 1884, p. 78, plate I1) shows many striking resemblances. Waite states that 
the quadrate is not completely closed behind, but that there is a posterior notch, wide but not 
deeply cleft. On the other hand his figure (op. cit., plate xxvi, fig. 3) appears to show dis- 
tinctly that the stapes entered the tympanic cavity by a hole in the quadrate, just as it does 
in Trionyx. If this conclusion is correct, this differentiates the family from the Derma- 
temydide; as does also the wide separation of the pterygoids by the palatines and the basi- 
sphenoid. 
It seems not unreasonable to suppose that from the Dermatemydidz there sprang the 
Emydidz and the Chelydridae. From the least differentiated Dermatemydide, as ddocus, 
the Emydide differ especially in the lack of intergulars and inframarginals; but both these 
series of scutes might cease to be developt. In one of the earliest of the Dermatemydidz 
there are no inframarginals, except at the axillary and inguinal notches. Were it not for the 
intergulars and the extraordinary sculpture of Basilemys we might regard it as an Emyd. 
) 
