128 HERPETOLOGY OF MICHIGAN. 



istics of this suake. A most excellent account may be found in 

 Stejneger's "The Poisonous Snakes of Xorth America" (1893, 

 413). 



Range: The species has been reported from: Michigan (Sager, 

 1839, 302; Holbrook, 1842, III, 32; Miles, 1801, 233; Stejneger. 1893, 

 413, Grosse Isle (Baird and Girard, 1853, 14, 15), Ann Arbor 

 (Smith, 1879, 6), Xew Buffalo, Berrien County (Cope, 1900. 1149), 

 Eaton County (Clark, 1902, 194), Benzonia to Au Sable River 

 (Clark, 1905, 110), Cass County (Thompson, 1911, 107 j, and Huron 

 County (Ruthven, 1911a, 270-271). We have seen specimens from 

 Alma, Gratiot County, Au Sable River, Oscoda County, Pontiac, 

 Oakland County, various localities in WashtenaAv County, Charity 

 Island, Sagina\v Bay, Cass County, Stony Island. North Island and 

 Sand I*oint, Huron County. 



ORDER TESTUDINATA. ( TURTLES ) . 



As indicated by the ke^^ (p. 77) the members of this order are 

 quadrupedal, cuirassed forms with a rounded or longitudinal anal 

 opening. The shell in our species is, with the single exception of 

 the soft-shelled turtle, covered with large dermal plates. Sieben- 

 rock (1909) divides the order into four superfamilies only two of 

 Avhicli have representatives in Michigan. It is sufficient for our 

 purposes to diagnose the genera and species. 



Key to the Genera and Species of MU-higaii Turtles. 



a^ Carapace covered by leathery skin, and Avithout horny epider- 

 mal plates Plat ij pelt is spinlfera, p. 129. 



a-. Carapace rigid and covered with horny epidermal plates. 



b^. Plastron narrow, not nearly filling the opening of the cara- 

 pace, 

 e^. Bridge long and narrow. Tail long and furnished 

 above with a median row of large horny tubercles. 

 Marginal scutes '2'^. . . Xliehjdra serpentina, p. 133. 

 C". Bridge short and rather wide. Tail in males with a 

 terminal nail, and without a median dorsal row of 



tubercles. Marginal scutes 23 



Kinosternon odoratuni, p. 137. 



b-. Plastron nearl}- or quite filling the opening of the cara 

 I^ace. Marginal plates 25. 

 e^. Parts of plastron immovably attached to each other 

 and to the carapace, 

 d^ Carapace smoothly rounded, i. e., with no median 

 dorsal keel. 



