Beptilia and Batrachia of Wisconsin. 161 



ORDER OPHIDIA. SNAKES. 



Body covered with imbricated scales; beneath with a single row of band- 

 like scales (gastrosteges) as far back as the anus. Represented in this state 

 by two families. 



KEY TO THE FAMILIES OF SNAKES. 



1. Both jaws with ungrooved coiiical teeth; tail tapering, plates underneath 



(Urosteges) in pairs, without a rattle ; no pit in front of the eyes ; head 



more or less oblong, and usually tapering gradually into the neck Colubridce. 



2. No soUd teeth, or but few in the upper jaw ; jaw provided with gi'ooved 



erectile poison fangs; tail provided with a rattle; Urosteges undivided, at 

 least anteriorly; a pit in front of each eye; scales carinated ; head separ- 

 able from the body aud more or less triangular Crotalidce.. 



FAMILY CROTALID.E. THE CROTALID SNAKES. 

 Represented by two genera and two species. To this family belong some 

 of the most deadly poison snakes. 



KEY TO GENERA OF CROTALIDiE. 



a. Head covered with small scales, tail with large rattle Crotalus. 



h. Head covered with nine large plates; tail with rather small rattle. . Crotalophorus, 



CROTALUS, L. 



C. durissus, L. Yellow Rattle Snake. Banded Rattle Snake. 



Sulphur brown with darker in blotches or arranged, more or less regu- 

 larly, in ba7ids; head very triangular and ugly; dorsal scales in 23-25 rows; 

 G. 170-180; U. 23-28; L. 3 to 5 ft. In rocky places; rare. Formerly this 

 species was very common, but it is seldom met now. It may be found in 

 the rocky bluffs of our larger rivers. Very poisonous. 



CROTALOPHORUS, L. 



C tergeminns. , Holb. Massassauga or Prairie Rattlesrake. 



Color bi-ownish, " iSpots of dark brown margined with black, and exterior 

 to this a still lighter circle; vertebral blotches, 34 in number, almost quad- 

 rate, notched in front and behind, and extending from neck to tail; 2 to 

 3 series of lateral blotches on each side varying from circular to oblong " 

 (Smith). There are other series of lighter lines, but the above will be suffi- 

 cient to determine the species. Dorsal scales 25 rows; G.140-150; U. 25-30; 

 L. 2-3 ft. : not rare; in grassy marshes througliout the state. Poisonous. 



Variety Kirtlandii, Holb. 

 Much darker and moi'e uniform, with darker blotches above. Walworth 

 comity; rare. W. H. Smith in the State Survey of Ohio says,* — " The 



* Vol IV, p. 674. 

 K 



