KEY TO THE PRINCIPAL SPECIES OF LAND AND 

 FRESH' WATER TURTLES 



L Limhs like flippers 



Marine Turtles 

 Limbs not like flippers; with feet for crawling 2. 



2. Shell soft and leathery; Family Trionychidae Soft-shelled Turtles, 



Leatherbacks, Flapjacks 3. 



Shell composed of bony plates 6. 



3. Anterior border of carapace smooth; no longitudinal ridges on the sep' 



turn dividing the nostrils; Mississippi drainage, Colorado River 

 Amyda mutica (LeSueur) Brown Soft-shelled Turtle, 

 Leatherback 

 Anterior border of carapace with tiny, conical, spine-like projections 

 (sometimes absent in the young) ; with a longitudinal ridge in each 

 nostril along each side of the septum dividing the nostrils 4. 



4. With two light bands on the head uniting at the base of the snout; young 



with black-edged dark spots on the carapace; Mississippi and St. Law 

 rence drainages 



Amyda spinifera (LeSueur) Spiny Soft-shelled Turtle, Flap' 

 jack 

 With two light bands or faint stripes on the head uniting a little before 

 the eyes 5. 



5. Carapace oval; carapace of young with a light network separating large, 



dark blotches; S. C. to Florida and Louisiana 



Amyda ferox (Schneider) Southern Soft-shelled Turtle 

 (Trionyx ferox (Schneider) ) 

 Carapace wider behind; carapace with light tubercles; Okla. to Louisiana 

 and California 



Amyda emoryi (Agassis) Southwest Leatherback 

 (Aspidonectes emoryi Agassiz) 



6. Plastron small, cross-shaped, or else with two transverse, cartilaginous 



joints and composed of nine to eleven (rarely twelve) plates 7. 



Plastron large, composed of twelve plates, and with one or no transverse 



hinge; Family Testudinidae 18. 



7. Tail almost as long as the shell and with one or more rows of tubercles 



along the upper surface; plastron small, cross-shaped, without trans- 

 verse joints; carapace flattened and with flaring edges; Family Chely 

 dridae Snapping Turtles 8. 



Tail much shorter (except in the very young) and without tubercles; 

 plastron large or small, with two transverse, cartilaginous joints; cara' 

 pace high, with the edges turned downwards; Family Kinosternidae 

 Mud and Musk Turtles 10. 



8. Tail with small scales beneath; with three high, lengthwise ridges on the 



carapace; edge of carapace with extra marginal plates; 111. south; Ga. 

 to Fla. and Texas 



Macrochelys temminc\ii (Troost) Alligator Snapper 

 (Macrochelys lacertina (Schweigger) ) 



430 



