114 HIGH SCHOOL ZOOLOGY. 



purposes. Snakes which are destitute of a rattle have been observed to 

 make a rustling noise with the tail, and it is interesting in considering 

 the origin of the rattle to recognize that each successive ring is merely 

 the retained slough of the tip of the tail. 



By the absence of a rattle, the presence of cephalic shields, and the 

 smaller size, tlie Copperheads, Aiicidrodou coiUortrlx, are readily dis- 

 tinguished from the Rattlesnakes, which they resemble, however, in 

 being very venomous. They are found in less rocky ground than the 

 foregoing, are somewhat more active in tlicir habits, but seek similar 

 prey, viz., small animals, birds and frogs. 



Of the ColubridiB the Garter Snake, Eutcenia slrtalia, is cei-tainly the 

 conmionest. Its dorsal scales are cariiiated, and arranged in nineteen 

 rows, while those of the ventral surface of the tail are undivided. An 

 allied species, E. saurita, the Swift Garter Snake, is much slenderer, 

 and has a longer tail. 



The Garter Snakes affect damp swampy places, take readily to water, 

 and are gregarious in their winter quarters. They are viviparous like 

 most aquatic snakes. The commonest Water Snake is Tropldonotm 

 s'qirdon, which is to be seen basking on the shores of streams, to which 

 it takes when startled. Another common form is Storeria Dekai/i, the 

 Little Brown Snake. It is also aquatic and insectivorous in its habits ; 

 its dull colours present a strong contrast to the bright green of the Grass 

 Snake, CijdopMs vcrnalls, a form which lives in marshes, and attains a 

 length of eighteen inches. Two larger species, the Black Snake, Bas- 

 caiilum constrictor, and the Fox Snake, Coluber vulphms, prey upon 

 larger animals such as mice and frogs, and attack birds' nests. Both of 

 these species attain a length of five or six feet. The one is to be recog- 

 nized by its i;niform black colour, while the other is light brown with 

 darker blotches. Finally the Milk Snake may be mentioned, Ophiholus 

 trlancjidas, a whitish snake with oval brown blotches edged with lilack, 

 found in dry situations, and visiting dairies for the milk ; the Ring- 

 necked Snake, Dladophis punctatiis, with its characteristic yellow ring, 

 and lastly tlie Hog-nosed Snake, Heterodon platyrhlnus, a peculiar form 

 generally supposed to be venomous, which has the habit of distending 

 its neck with air so as to look formidable, and then emitting the air 

 with a hissing sound, whence it is also called Blowing Viper. In the 

 poisonous genus Naja, a similar formidable appearance is secured by the 

 stretching out of the foremost free ribs at right angles to the vertebral 

 coluum, so that the neck is converted into a flattened disc. 



