532 The American Naturalist. [June, 
1822. Chelonea, Fleming, Philos. of Zool., Vol. If., p. 268, 
Edinburgh, 1822. 
1825. Fornicata, Haworth, A. Tilloch, Phil. Mag., LXV., 
1825, pp. 372-373. l 
1828. Sterrichrotes, Ritzen, F. F. A., Nova Acta Nai. Cur., 
1828, Vol. XIV., Bonn, 1828. 
1834. Chelonia, Carus, G., Lehrbuch der Vogl., Zool. Aufl. 
L, Theilp. 25, Leipzig, 1834. ‘ 
The Athece-—I have shown in a paper published some time 
ago,” that the group Athece, or Athecata, as spelled by Lydekker, 
is an unnatural one, and that its members belong to the Pinnata, 
or sea-tortoises. I do not need to discuss this question fully again 
on this plate; I shall only give my principal reasons. 
Protostega and Protosphargis, which are placed by Boulenger, 
Lydekker, Döderlein, among the Athecæ, are near the Chelonii- 
dæ. In both true marginal bones (peripheralia) are developed. 
The skull of Protostega is like that of the Cheloniidæ ; there is a 
free epipterygoid, and the descending processes of the parietals 
are present ; also an ossified articular bone. Humerus and cora- 
coid are in shape between those elements in Dermochelys and 
Cheloniidæ. It seems that Lydekker is inclined lately to accept 
my idea of the relationship of the Athecæ, for he says in the in- 
troduction to his Catalogue of Fossil Tortoises: “ If the skull re- 
ferred by this writer (Baur) to Protostega be rightly assigned, 
there will be evidence of a closer connection between the two 
groups (Cheloniidæ and Protostegidæ) than has hitherto been 
supposed. The skull from which I took these remarks is cer- 
tainly rightly assigned,” for it is the type of Protostega, and all 
the above points are mentioned by Prof. Cope® in his description, 
with figures, of Protostega; even Lydekker, who still sustains 
the Athecz, will have to admit now that at least the Protostegidz 
5Baur, G. Die systematische Bemerkungen über die systematische Stellung von 
ê Cope, E. D., The Vertebrata of the Cretaceous Formations of the West. Rept. 
U. S. Survey Territ., Vol. IL., 1875. y 

