152 Annals of the Carnegie Museum. 



stripe, which is broad and conspicuous. This is the only record at 



hand for this subspecies within the county. 



i8. Eiitania sirtalis ordhiata (Linnaeus). Garter snake. 



This subspecies is met with occasionally. There are a number of 

 specimens of this subspecies in the collection of the Carnegie Museum, 

 coming from widely different points in the county. It is smaller 

 than Eutcenia sirtaUs, and not so heavy in build. In captivity its 

 habits are about the same as those of the other species. 



19. EufcTiiia sirfalis seinifasciata Cope. Garter-snake. 



There is a specimen in the collection of the Museum, taken by the 

 writer at McKee's Rocks, September 14, 1900, which is referable to 

 this subspecies. In many specimens the spots extend into the median 

 dorsal stripe, but in the present specimen they meet, giving it a banded 

 appearance. 



Family CROTALIDiE. 



This family is represented in western Pennsylvania by three genera, 

 each represented by a single species, and includes all the poisonous 

 snakes occurring in the State. Only one of these species occurs at the 

 present time in Allegheny County. 



Key to Local Genera of Crotalid.'E. 

 A. Tail having no rattle ; scales in twenty-three rows. Ancisirodon. 



AA. Tail having a rattle. 



B. Head with the nine normal head-shields Sisirurus. 



BB. Head having vertical and occipital head-shields replaced by numerous small 

 scales. Crotahts. 



Genus Ancistrodon Beauvois. 



20. Ancistrodon contortrix (Linnaeus) . Copperhead. 



This is the only species of poisonous snake found in Allegheny 

 County at the present time. It is not rare in some localities, where 

 its retiring disposition and powers of concealment have preserved its 

 existence for many years, after both species of rattlesnakes have be- 

 come extinct. It can easily be recognized by its thick body, triangular 

 copper-colored head, the pit between the eye and the nostril, vertical 

 elliptical pupils, and the pair of erectile fangs in the upper jaw. 



While the copperhead is a sullen and treacherous snake, its disposi- 

 tion is to remain concealed, and it will not strike unless closely pressed, 

 or trod upon. It is of a sluggish nature, unable to crawl rapidly, and 

 seems to prefer the evening to hunt for food. In captivity they ob- 

 stinately refuse to eat, but will drink water readily. Slugs, birds and 



