Tail with two rows of large shields beneath; with three low, lengthwise 

 ridges on the carapace; edge of carapace with a single row of marginal 

 plates 9. 



9. With two small chin barbels; with one row of larger tubercles along the 

 mid line of the upper surface of the tail; U. S. east of the Rockies, 

 excepting Florida 



Chelydra serpentina serpentina (Linn.) Common Snapper 

 With four small chin barbels; with three or four rows of nearly equal 

 tubercles along the upper surface of the tail; Florida 



Chelydra serpentina osceola (Stejneger) Florida Snapper 



10. Plastron short and narrow, not capable of closing shell; central margin of 



pectoral plate as long as humeral 11. 



Plastron covering the soft parts, capable of almost or entirely closing the 



shell; central margin of pectoral plate shorter 13. 



11. With two yellow stripes on each side of head; chin with lengthwise 



stripes; U. S. west to Okla. and Texas 



Sternotherus odoratus (Latreille) Common Musk Turtle, 



Stink Pot 

 (Aromochelys odoratus (Latreille) ) 

 No or faint head stripes; chin spotted or mottled 12. 



12. Head spotted with black; carapace with a mid-dorsal keel in both young 



and adult; southern Mississippi drainage 



Sternotherus carinatus (Gray) Keeled Musk Turtle 

 Sides of head with faint stripes; with a lateral keel on each side of cara- 

 pace; mid'dorsal keel present only in the young; Tenn. to Fla. and 

 Ala. 



Sternotherus mmor (Agassiz) Southern Musk Turtle 

 (Aromochelys tnstycha Agassiz) 



13. Bridge (connection between the plastron and the carapace) very narrow, 



about one-third as long as the length of the plastron before the first 

 transverse hinge; head plain dark or light speckled above; sides of neck 

 with one or two faint stripes; Florida 



Kinosternon steindachneri Siebenrock Florida Mud Turtle 

 Bridge about one-half as long as the front lobe of the plastron 14. 



14. Sides of head striped 15. 

 Head spotted, blotched, or plain colored, the spots arranged in length- 

 wise rows on the neck in K. suhruhrum suhruhrum 16. 



15. Sides of head with two narrow, light stripes; with three yellow stripes on 



the carapace, which become faint in old turtles; Florida 

 Kinosternon haurii Garman Banded Box Turtle 

 With two wide orange bands on each side of the head; no stripes on the 

 carapace; Mo. to Ala. and Texas 



Kinosternon suhruhrum hippocrepis (Gray) Louisiana Mud 



Turtle 

 (Cmosternum louisianae (Baur) ) 



16. Top and sides of head with yellow spots and blotches, which are arranged 



in two lengthwise rows on each side of the head; eastern U. S. to 

 Florida, 111. and Tenn. 



432 



