FOSSIL VERTEBRATES — REPTILIA 727 
Remains of the closely related forms that culminated in the 
Cheloniide ( Chelonia, etc.) and differed from the previous forms 
only in the more complete carapace, are found in the Cretaceous 
of Europe and America. These forms show characters of the 
land turtles as well as of the sea turtles, and are in all probability 
the forms that represent the branching of the primitive stem of 
the turtles. Such forms are Propleura, from the Cretaceous of 
New Jersey, Osteopogys, from the same locality, Toxochelys, from 
the Niobrara, Cretaceous, of Kansas, and Euclastes from the Cre- 
taceous of New Jersey, the Greensand of Cambridge, England, 
the Eocene of England and France. Forms more common on 
the continent are Eurysternum, from the Upper Jurassic of Ger- 
many, /dvochelys, from the same horizon in France (Cerin) and 
Germany (Kelheim). AHydropeltz is quite frequently found asso- 
ciated with the remains of /dzochelys. 
Of the common swamp and land turtles more is known than 
of the sea turtles. The ancestors of the Chelydride@, or common 
snapping turtles, are found as far back as the Upper Jurassic. 
Platychelys from this horizon, at Kelheim, is one of the typical 
forms. In Flatychelys there was an extra pair of plates in the 
plastron, the mesoplastra, that did not reach the middle line 
from the sides. 
Flelochelys, from the Greensand (Cenomanian) of Kelheim, 
was quite similar to the preceding. The whole surface of the 
carapace was covered with wart-like projections, except the lines 
that marked the union of the horny plates with the bony ones 
beneath. In this form the mesoplastron was narrow but com- 
plete, and extended from each side, meeting in the middle line. 
It was quite large, about a foot and a half long. 
Compsemys is a very large form, distinguished by the fact that 
the plates of the carapace are joined by suture to the peripherals, 
and are marked by small pit-like excavations. It is very plenti- 
ful in the Upper Cretaceous layers (Fort Union and Laramie) of 
the western part of this country. 
Anostira was a small form from the Lowest Eocene (Bridger) 
in Wyoming. 
