208 Trans. Acad. Sci of St. Louis. 



ing the body from side to side in an effort to twist itself 

 free and often in its excitement unconsciously throwing 

 a portion of its body against the widely distended jaws 

 with their sharp fangs, which immediately close, inflicting 

 a wound upon itself, which is never mortal, as the ven- 

 omous snakes are immune to their own and to each other 's 

 poison.^' (Ditmars.) 



The venom of the Copperhead is to my experience more 

 virulent than that of the Cotton Mouth and the smaller 

 Rattle Snakes. This snake is a much more vicious animal 

 than the Rattlesnake, not only because it strikes without 

 giving any warning, but also because it is of a much more 

 aggressive nature and quick in its movements. Dr. R. E. 

 Kunze (American Naturalist, 17:1229. 1883), thinks that 

 the Copperhead does not strike from a regular coil, like 

 the Rattlesnake, but that its effective blow is delivered 

 when the middle of the body is thrown into long, almost 

 rectangular curves, and the head held only slightly ele- 

 vated above the ground. The Copperhead is ovo vivipar- 

 ous, producing from four to nine young ones. July 27, 

 1895, when dissecting one of these snakes I found thirteen 

 embryos, each about 3" (76 mm.) long. 



Dates of capture. — April 4; May 6; June 23; July 27; 

 September 1, 30. 



Genus sistrurus. 



A pair of large erectable, perforated poison fangs in front of upper 

 jaw; no other maxillary teeth. Loral pit and rattle present. Top of 

 head covered with large plates, scales keeled, with pits in 21 to 25 

 rows. Anal and subcaudals not divided. Size small to medium. 



Key to the Species in Missouri. 



Postnasal in contact with preocular. The light line to angle of 

 mouth begins at nostril. catenatus. 



Postnasal separated from preocular by loral. Light line to angle 

 of mouth begins at the eye. miliarius. 



