124 G. R. Wieland — Upper Cretaceous Turtles. 



limbs or peduncles however pass gradually beneath the pos- 

 terior edge of the seventh, and end as mentioned, in the ante- 

 rior pit of the eighth marginals. 



(2) Horn Shields. — The boundaries of the plastral horn 

 shields are not all distinct, and these being the only portions 

 whatsoever of either carapace or plastron that are not entirely 

 so, it has been deemed best to indicate them, so far as deter- 

 mined, separately in text figure 4. As there shown, the infra- 

 marginal region is not clear. The anterior border of the pec- 

 torals, ventrals and femorals is however distinct, anals not 

 being present, or else diminutive as in Chelydra. The gular 

 boundaries do not show clearly, but these elements were prob- 

 ably small as in the existing Staurotypus Salvinii, with which 

 there is in the general arrangement, number and size of parts 

 a fairly striking comparison. 



(C) Limb and Other Bones. — The humerus, as shown in 

 text figure 6a, is in part intermediate between what I have 

 termed the chelic (Chelydra) and the parachelic \Testudd) 

 form.* The proximal end approaches the Chelydran form 

 very distinctly. It is very large and the shaft slender. But 

 the distal end is facetted, and in this respect approaches the 

 grooved character seen in some forms of Testudo. The ectepi- 

 condylar foramen is a deep perforation. The only well-marked 

 suggestion of departure in the direction of marine forms is 

 afforded by the obtuse angle between the radial and ulnar 

 crest, this being markedly greater than in Chelydra. 



The femur, as might well be surmised in Osteopygis from 

 the oval outline of the carapace, is as in Chelydra distinctly 

 larger than the humerus (see figure 6 a and b in text). The 



Figure 7. — Osteopygis Gibbi type. 

 C, superior view of seventh cervical centrum ; A, superior view of first, 

 and B, of the second left Metatarsalia ; U, outer view of left Ulna ; T, outer 

 view of right Tibia. 



* Some Observations on Certain Well Marked Stages in the Evolution of 

 the Testudinate Humerus, this Journal, vol. ix, 1900, 413-424. See also, 

 L'Evolution des Ch^loniens Marin par L. Dollo, Bull. Acad. Roy. Belgique 

 CI. Sc. (Aug. 9, 1903). 



