316 SERPENTS. 



and frequently scarce visible: the general rule, 

 therefore, is, that all venomous serpents have only 

 tuo ro\\s of true or proper teeth in the upper jaw, 

 and that all others have four. 



A head entirely covered with small scales is in 

 some degree a character, but by no means a uni- 

 versal one, of poisonous serpents; as are also ca- 

 rinated scales on the head and body, or such as are 

 furnished with a prominent middle line. 



All Serpents are in the habit of casting their 

 skin at certain periods; in temperate regions annu- 

 ally ; in the warmer perhaps more frequently. The 

 serpents of the temperate and cold climates also 

 conceal themselves, during the winter, in cavities 

 beneath the surface of the ground, or in any other 

 convenient places of retirement, and pass the win- 

 ter in a state more or less approaching, in the dif- 

 ferent species, to complete torpidity. It may be 

 added, that some serpents are viviparous, as, the 

 Rattle-Snake, the Viper, and many others of the 

 poisonous kind, while the Common Snake, and 

 probably the major part of the innoxious serpents, 

 are oviparous, depositing their eggs in a kind of 

 string or chain in any warm and close situation, 

 where they are afterwards hatched. 



The broad undivided lamina; or scaly plates on 

 the bellies of Serpents are termed scuta, and the 

 smaller or divided plates beneath the tail are called 

 squama: subcaudales, orsubcaudal scales, and from 

 these different kinds of lamina, 1 the Linnxan ge- 

 nera of Serpents are chiefly instituted. 



