MARYLAND GEOLOGICAL SURVEY 63 



Trionyx sp. 



Trionyx sp. Cope, 1867, Proc. Acad. Nat. Sci. Phila., voL xix, p. 143. 



Description. — " An uncharacteristic portion of the carapace, which 

 exhibits larger and more regular pits [than T. cellulosus], separated by 

 wider partitions. The pits at one extremity are larger than those of 

 the other, and the septa narrower." Cope, 1867. 



Occurrence. — Calvert Formation. Charles county near the Patux- 

 ent river. 



Collection. — Formerly in the Philadelphia Academy of Natural 

 Sciences. 



Suborder CRYPTODiRA. 

 Family CHELONIDAE. 



Genus CHELONE Linne. 



Chelone, sp. 



Chelone sp. Cope, 1867, Proc. Acad. Nat. Sci. Phila., vol. xix, p. 143. 



Description. — " A proximal jjortion of the costal plate has a thick- 

 ness of three lines, but rapidly thins out. Its surface exhibits trans- 

 verse rugae at its proximal extremity; elsewhere the rugge are longitu- 

 dinal, and more distinct on one side than the other." Cope, 1867. 



Occurrence. — Calvert Formation. Near the Patuxent river in 

 Charles county. 



Collection. — Formerly in the Philadelphia Academy of Natural 

 Sciences. 



Chelone sp. 



Chelone sp. Cope, 1867, Proc. Acad. Nat. Sci. Phila., vol. xix, p. 143. 



Description. — " Two fragments of the carapace of a large and convex 

 species, each with a strongly marked groove for the margin of the dermal 

 shields. The surface is without sculpture.^^ This specimen was found 

 with the one previously described. 



Occurrence. — Calvert Formation. Charles county near the Patux- 

 ent river. 



Collection. — Formerly in the Philadelphia Academy of Natural 

 Sciences. 



