REPTILES. 77 



Another general fact of distribution may be pointed out, namely, 

 that there is a western element in the fauna of the northern penin- 

 sula. This is at present only shown by the occurrence of Chrijsemys 

 helUi in that region, but it is in harmony with what has been 

 shown to occur in other groups. 



KEYS TO THE ORDERS AND SUBORDERS OF MICHIGAN REPTILES.* 



a^ Body elongate and covered with small scales. Anus a cross- 

 slit. Order Squamata (Lizards and Snakes). 



b^. Limbs present. Eyelids movable. An external ear 



opening. Suborder Sauria (Lizards), p. 77. 

 b^. Limbs absent. No external ear opening or movable 

 eyelids. Suborder Serpen tes (Snakes), p. 81. 

 a^. Body short and broad and enclosed between two (upper and 

 lower) shields. Limbs present. Anus rounded or a longi- 

 tudinal slit. Order Testudinata (Turtles), p. 128. 



ORDER SQUAMATA — SUBORDER SAURIA (lIZARDS). 



Description: As indicated by the key, the lizards of Michigan 

 may always be known from the other reptiles by the combination of 

 characters, presence of small scales over the body and of four limbs. 

 As already said, they are frequently confused with the salamanders 

 but may always be told from them by the fact that the skin is never 

 smooth and moist. 



Key to the Genera and Species of Michigan Lizards. 



a^. Body covered above with fine tubercular scales. Tongue deeply 



bifid. Cnemidophorus sexUneatus (L.)t 

 a^. Body covered above with* rather large, imbricated scales. 



Tongue slightly notched. Eumeces quinquilineatus (L.). 



EUMECES QUINQUILINEATUS (Linnaeus). 



BLUE-TAILED SKINK. 

 (PI. VIII.) 



Plestiodon vittigerum,% Hallo well, 1856, 310. 

 Eumeces fasciatus, Smith, 1879, 6. Clark, 1905, 110. 

 Eumeces quinquilineatus, Cope, 1900, 637-638. Ruthven, 1911a, 

 263-264. 



*It is hardly necessary to say that the keys in this paper are highly artificial. They are 

 designed only to to furnish an easy and efficient means of identifying the species. 



tThe genus Cnemidophorus has not heen recorded from this state, so it will not be considered 

 further in this work. C. t^exlineatus occurs in northern Indiana, however, and is to be looked 

 for in southwestern Michigan in the sand dunes along Lake Michigan. 



JThe synonomy given under each species includes only papers that refer to Michigan speci- 

 mens. 



