Beptiles and Amphibians of Illinois. 201 



have not had such fictions recounted to them by nurse, or 

 parent, or playmate, show no fear when serpents are first 

 brought into their presence. The truth is that the number of 

 poisonous species of a given region is not often large. In 

 Illinois we have but four poisonous serpents in a total of about 

 forty species; and the proportion of noxious to innoxious spe- 

 cies is probably not much greater anywhere in the country. 

 At the same time it must be acknowledged that the prevalent 

 fear of snakes serves a very useful purpose in keeping children 

 from being bitten by species really poisonous. The harmless 

 kinds take advantage of the feelings they inspire, and simulate 

 the behavior of their formidable relatives by coiling, striking, 

 and even producing a semblance of th(3 noise of the rattlers 

 by causing the tail to vibrate rapidly in contact with dead 

 vegetation. All, or nearly all, will use the teeth when pressed, 

 but the bite is not followed by serious consequences. 



We have no very large species. Certain of the boas and 

 pythons of tropical countries reach a great length — as much 

 as fifty feet or more, it is asserted. The smallest, among which 

 are our species of Carphophis, are not above a foot long. 



The food consists of living animals, generally swallowed 

 alive, but sometimers picked up after having been killed by 

 other agencies. The teeth serve merely as organs of prehen- 

 sion, and the fangs, when present, are used only in striking. 



The young hatch from eggs, which are commonly deserted 

 after being placed among decaying vegetable matter; but some 

 species are known to guard them until the young come forth. 

 Some are, it is believed, habitually ovoviparous; and from ob- 

 servations made on our common species it is evident that many, 

 at least occasionally, produce living young. 



Without fangs. Pupil of eye round. No pit between eye and 

 nostril. Two series of subcaudal plates Colubrid.^. 



With fangs. Pupil of eye vertical. A pit between eye and 

 nostril. Some or all of subcaudals united. . . .Crotalid.e. 



Family COLUBRID^. 



Teeth numerous, used only for prehension, the posterior 

 ones sometimes larger than the others and grooved. With- 



