14 Annals of the Carnegie Museum. 



Explanation of Plates. 



Plate I. Thalassochelys caretta, Delaware Bay. Ectal view of plastron. X §• 

 Plastral type of the Cheloniidse, except the Protosteginse, with narrow in-turned epi- 

 plastra. The ventral horn-shield, or that imbricating over the hyo-hypoplastral junc- 

 tion, is the only one likely to be clearly indicated in fossil plastra of this type. 



Plate II. Chelone mydas (var. or sp. nov.). Southern Atlantic coast of the 

 United States. Plastron with marginals (less nuchal) placed in natural position very 

 nearly. More reduced than the preceding. 



