TESTUDINATA: TRIONYCHID.E. 291 



The Genus Chelydra contains the Common Snapping- 

 Turtle, C. serpentina, Schw., from Canada to Florida and 

 westward to the Missouri, which is found of all sizes, 

 from a few inches to a total length of four feet. It 

 has two long, flexible warts on the chin, and a crest of 

 wedge-shaped tubercles on the tail. This turtle exhibits 

 its ferocious disposition even before it is hatched. 



TRIONYCHID^, OR TRIONYX FAMILY. This Family 

 comprises turtles which have the body fiat, circular, 

 slightly elongated, the shield more or less flexible, or 

 not completely ossified, neck and head long, the latter 

 terminated by a long leathery snout, feet broad and 

 webbed, five-toed, but with only three nails to each foot. 

 They inhabit principally the muddy bottoms of shallow 

 waters, often burying themselves in the soft mud, leaving 

 only the head exposed. They take breath from time to 

 time by carrying the snout above the water without even 

 moving the body. They feed upon small animals ; and 

 lay from twelve to twenty or more spherical eggs, with a 

 thick and very brittle shell. Three genera and about 

 half a dozen species belong to North America. 



The Genus Platypcltis contains the Soft-shelled Turtle, 

 P.fcrox, Fitz., Trionyx fcrox, Sch., of the Southern States, 

 which attains sixteen inches in length ; color umber- 

 brown above, with dusky blotches ; below white, marked 

 by the red bloodvessels. 



The Genus Amy da is represented by A. mutica, Fitz., 

 of New York and southward and westward ; and Aspido- 

 ncctes, by A. spinifer, Ag., from Lake Champlain to the 

 Rocky Mountains. 



The Sub-Order of Chelonii, or Sea-Turtles, comprises 

 Testudinata which are perfectly adapted for swimming, 

 or flying through the water, and which never leave the 

 sea except to lay their eggs, which are placed near the 

 shore in the sand. It contains Chelonioidae or Logger- 

 head Family, and Sphargididae, or Sphargis Family. 



