BRANSON : SNAKES OF KANSAS. 417 



CROTALIDiE. 



The Crotalida- or Pit Vipers are represented in Kansas by 

 four, possibly five, species. These are the only poisonous 

 snakes that occur in the state. They may be distinguished 

 from liarmless snakes by the presence of a pit between the eye 

 and the nostril, and by their having near the front of the upper 

 jaw a pair of large, perforate, erectile fangs. 



KEY TO GENERA. 



I.— No rattle Ancisirodon. 



II.— A rattle. 



1. Top of head with platea Sistrurus. 



2. Top of head with scales Crotalus. 



ANCISTRODON Beauvois. 

 Toxicophis Troost, .\nn. Lye. Nat. Hist. N. Y., Ill, 1833, p. 190. 

 Ancistrodmi Baird, Serp. N. V., 1854, p. 13. 

 Afjkistrodon Beauvois, Trans. Amer. Phil. Soc, IV, 1799, p. .381. 



Nine cephalic plates. A pit between the eye and the nostril. 

 A pair of erectile poison fangs. Scales keeled, in 21-27 rows. 

 No rattle. Anal entire. 



KEY TO SPECIES. (STEJNEGEB.) 



1. A loreal; orbit separated from supralabials by scales; usually 23 scale rows. 



A. contnrtrix. 



2. No loreal; supralabials entering orbit; 25 scale rows A. piscivorus. 



No specimen of A. piscivorus has ever been reported from Kan- 

 sas, but every water snake found in our streams is called Water 

 Moccasin. These harmless snakes have got a bad reputation 

 from being aquatic. The poisonous Moccasin is easily distin- 

 guished from the harmless water snakes by the presence of the 

 pit, by the erectile fangs, and by the thickness of the body. 



I think it very probable that A. piscivorus occurs in south- 

 eastern Kansas, as it is found in southern Missouri and in Ar- 

 kansas, and probably enters Kansas by way of the streams 

 flowing from Kansas into these states. The description here 

 given is taken from Stejneger. 



