AUSTRALIAN SNAKES 267 



the body is bulky and bloated. Rattlesnakes 5 ft. long 

 are not uncommon, and one species attains a length 

 of 8 ft. The headquarters of the genus are Northern 

 Mexico, but the species are distributed from Canada to 

 Argentina. Rattlesnakes as a rule prefer prairie and 

 rough rocky waste-lands, where they can bask in the sun ; 

 but some species are found, at any rate seasonally, in 

 forest, and some of the largest species have a preference 

 for cane-brake and swamp. Rattlesnake venom is 

 markedly haemolytic, and, quite apart from. its action 

 on the blood and vessels, has a direct depressing effect 

 upon the heart. 



(d) Sistrurus. The small snakes of this genus are 

 known as Pigmy Rattlesnakes and are restricted to 

 North America, from Canada to Mexico : they differ from 

 Crotalus in having the head covered with large sym- 

 metrical shields, and in their slender make and small size, 

 none of them attaining a length of 3 ft. 



THE THANATOPHIDIA OF AUSTRALIA, exclusive of the 

 numerous sea-snakes, number between sixty and seventy 

 species and are all Elapincv. The more notorious genera 

 and species are the following : 



(a) Denisonia (see p. 253). Over twenty species are 

 known. Denisonia superba is the Australian " Copper- 

 head." It is a brownish snake with a yellowish or reddish 

 tinge on the sides : the young have, on the neck, a black 

 blotch or ring which is sometimes edged behind with 

 yellow. 



(6) Diemenia. In this genus the maxilla is long for 

 an Elapine, and carries, besides the poison-fangs, from 

 seven to fifteen small grooved teeth. Seven species exist, 

 of which Diemenia textilis, the " Brown-snake," grows to 

 a length of over 5 ft., and is said to be more deadly 

 than the Indian cobra. 



(c) Notechis. This genus includes a single species, 

 Notechis scntatus, the " Tiger-snake," in which the scales 

 are oblique, those on the sides being somewhat shorter 

 than those on the back. Its colour varies from dull 



