1890. ] Classification of the Testudinata. 533 
e 
are very near the Cheloniidz, and belong certainly to the Pinnata. 
After it shall have been proved that in Protostega and Protosphar- 
gis an entoplastron is always absent, they will rank as a distinct 
family from the Cheloniidz, to be placed between the latter and the 
Dermochelyidz. I have shown now that Protostega and Proto- 
sphargis are true Pinnata; we have now to consider the remaining 
genera of the group: Dermochelys, Psephophorus, Eosphargis, 
and Psephoderma. I do not considergPsephoderma at all in this 
connection ; it is, so far, impossible to determine the exact sys- 
tematic position of this genus. Such dermal ossification as seen 
in Psephoderma may appear in any order of the Reptilia. I have 
shown that the absence of the descending processes of the parie- 
tals in the remaining three genera is an entirely secondary condi- 
tion, that all Testudinata possessed originally an epipterygoid and 
the descending processes, and that in the Pinnata the tendency is 
present to abort these processes. I have shown that the char- 
acter given by Boulenger to Dermochelys, that the lower border 
of the postfrontal joins the jugal and the squamosal, and is sep- 
arated from the quadratojugal by the two latter bones, does not 
hold, for it is also found in specimens of Chelonia. But to con- 
vince everybody that Dermochelys and its fossil allies, Psepho 
phorus and Eosphargis, cannot be separated from the Pinnata, I 
give the characters which are only found in the Pinnata, and 
in no other group of the Testudinata. These characters are: 
1. The foramen palatinum, between palate and maxillary, is 
absent. 
2. The articular faces between the sixth and seventh cervicals 
are plane. 
3. The nuchol has a distinct process on the lower side for the 
articulation of the neuroid of the eighth cervical. 
4. The small trochanters of the femur are united, and there is 
a fossa between these and the large trochanters. (This condition 
is also seen in the true land tortoises, Testudinidz). 
5. There is only one central line in the carpus; the intermedium 
reaches the first carpale, excluding the centrale from the radiale. 
The characters, with the exception of No. 4, are typical for the 
Pinnata, but they are also typical for Dermochelys. That the Dermo- 
Am, Nat.—June.—3. 
