96 G. R. Wieland—O'/i Marine Turtles. 



tionedas ''flattened" by Cope. Case figures as the first finger 

 what is here denoted as the second, but, as is further mentioned 

 below, there is a striking peculiarity in the strong resemblance 

 of the second metacarpal to the first, which would lead one to 

 err in this respect in the absence of tlie other digits. 



Descri])tion. The humerus, rather broader in the fossil 

 than in life as the result of crushing, is, as I have already 

 pointed out on the basis of the proximal portion only, of 

 the thalassoicl type characteristic of various of the older 

 Chelonidae.^ That is, while the general outline closely ap- 

 proaches that seen in typical oceanic turtles, certain persisting 

 older characters are present, such in particular as the high 

 position of the rather prominent radial crest. The most closely 

 related humei-al form is to be seen in LytoJoraa-\ and in 

 Neptunochelys tuberosa (Leidy, Cope) Wieland." 



The radius is somewliat longer than the ulna as in other 

 Chelonidan forms, and also be it noted as in AcicJielys {Eiiry- 

 siernur/i) Wagleri. (See figure in Zittel's Handbuch.) 



The large intermediura is also of the same general outline 

 as that of Acichelys.X The arrangement of the carpals is, 

 however, mainly as in Chelone^ etc., the first carpale not being 

 excluded from contact with the centrale, while the first meta- 

 carpal is set high, and the small and thin ])isiform is attached 

 to the fifth carpale. 



General Observations. The present is probably the first 

 fairly complete restoration of the fore flipper of an ancient 

 marine Chelonian which has been given, and as one might 

 Avell expect in the case of a Cretaceous turtle presenting vari- 

 ous primitive characters, no little light is shed upon the man- 

 ner in which the evolution of the Testudinate flipper has 

 proceeded. The most striking peculiarity is the flatness of 

 metacarpal II. This bone presents characters distinctly inter- 

 mediate to those of metacarpals I and III. As flattening is 

 usually only present in the bones of the first finger, there is in 

 Toxocheiys a very marked use made of this means of adapta- 

 tion for marine life. Toxocheiys has two well developed 

 claws, not noticeably differing in this respect from Eretrao- 

 chelys^ but tlie short and robust phalanges of the first and 

 second fingers, all of which are exceedingly well preserved, 

 are decidedly more suggestive of those seen in land forms than 

 in the case of any other known distinctly marine tm'tle. 



* G. R. Wieland. — Some Observations on Certain Well-marked Stages in 

 the Evolution of the Testudinate Humerus. This Journal, fourth series, 

 vol. ix, June 1900. 



f L. Dollo. — On the Humerus of Euclastes. Geol. Mag., vol, v, pp. 261- 

 267. London. 1888. 



X Zittel. — Handbuch der Paleontologie. 



