Page:The Osteology of the Reptiles.pdf/244

226 [. Leathery turtles. Marine turtles, with mosaic of small, polygonal, bony plates, in the dermis of the back, not ankylosed to the ribs.

Eocene. Psephophorus, Egypt, North America.

Recent. Dermochelys.]

. Marsh and river turtles, with reduced plastron loosely joined to carapace, the skull incompletely roofed. Entoplastron T-shaped. Caudals mostly opisthocoelous. Feet elongate, webbed.

Upper Jurassic. Tretosternum Owen (Peltochelys Dollo), Europe.

Eocene. Gafsachelys Stefano, Europe.

Miocene. ? Acherontemys Hay, North America. Chelydra, Europe.

Pleistocene and Recent. Macrochelys Gray, Chelydra Schweiger, North America.

. Temporal region not roofed. Plastron suturally united to carapace. No parietosquamosal arch. Caudals procoelous. Marsh turtles, the carapace well ossified.

Upper Cretaceous. Adocus Cope, Homorophus Cope, Zygoramma Cope, Agomphus Cope, Compsemys Leidy, Basilemys Hay, North America.

Eocene. Anosteira Leidy, Baptemys Leidy, Pseudotrionyx Dollo, Kallistira Hay, Notomorpha Cope, Alamosemys Hay, Basilemys Hay, Hoplochelys Hay, North America.

Oligocene. Xenochelys Hay, ? Anosteira Leidy, North America. Anosteira Leidy, Europe.

Trachyaspis Meyer, Eocene, Miocene, Europe, Africa.

. Temporal region not roofed. Neck retractile. Carapace low-arched. Subaquatic, the feet webbed. Middle digit rarely reduced. Marsh tortoises.

Upper Cretaceous. ? Gyremys Hay.

Eocene. Paleotheca Cope, Echmatemys Hay, North America. ? Chrysemys, Emys, Europe.

Oligocene. Graptemys Agassiz, North America. ? Clemmys Gray, Europe.