OPHIDIA: COLUBERID^:. 301 



teeth are adapted simply to seizing, killing, and retain- 

 ing prey, and are accordingly pointed, smooth, and arched 

 towards the throat. The tongue is long, slender, bifid, 

 extensible, and retractile within a sheath placed at the 

 root ; the eyes are without movable lids ; trachea very 

 long ; lung single, and extending nearly the whole length 

 of the body. Serpents cast their skins at least once a 

 year. They lay eggs with a calcareous, flexible shell ; 

 some of them, however, are ovoviviparous ; that is, the 

 eggs are hatched while still in the body of the parent. 

 This is especially true of venomous snakes. The Order 

 comprises a thousand or more known species. Baird and 

 Girard enumerate over thirty genera and a hundred and 

 nineteen species belonging to North America. 



BOIDJE, OR BOA FAMILY. This Family comprises ser- 

 pents which have both jaws armed with teeth, and rudi- 

 ments of hind limbs, or spur-like appendages. Some of 

 them are the largest of all serpents, attaining the length 

 of thirty to forty feet, and are able to swallow dogs, deer, 

 and even oxen, after having crushed them in their power- 

 ful folds. Such are the Boas and Anacondas of South 

 America, and the Pythons of Africa and the East Indies. 

 Wenona, with one small species found in Oregon, is our 

 only genus of this family. 



CoLUBERiDyE, OR COLUBER FAMILY. This Family 

 comprises serpents which have both jaws fully provided 

 with teeth, but have no rudiments of hind limbs. It in- 

 cludes a large proportion of all snakes, and is represented 

 in all countries where snakes are found. 



The Genus Entcenia Striped Snakes has the body 

 moderately stout, or slender, scales carinated, the skin 

 very extensible. The general color is three light stripes 

 on a darker ground, the intervals with alternating spots. 

 It is represented by several species in the United States. 

 Length twelve to thirty-six inches. 



