CLASS REPTILIA 559 



species are able to swim, and this, of course, is the normal method 

 of locomotion of the aquatic forms. 



The majority of snakes are oviparous, but some of them bring 

 forth their young alive. The idea that they swallow their 

 young in order to protect them and then spew them out again 

 when the danger has passed is erroneous. 



The tropics are more plentifully supplied with snakes than are 

 the temperate zones. Snakes are, however, found in many 

 places not inhabited by lizards. Madagascar seems to be the 

 only large country in warm and temperate latitude not inhabited 

 by dangerous snakes. As in the other groups of vertebrates, 

 the serpents are found in almost every kind of habitat; some 

 species live in salt water, others in fresh water; some are 

 arboreal; and many live underground. 



Only four of the nine families of SERPENTES occur in North 

 America. With a few exceptions those described below are 

 found in the United States. 



Family GLAUCONIID.-E. BLIND SNAKES. Two species of 

 these small, burrowing reptiles occur in the United States 

 Glaucoma dulcis, the Texas blind snake, in Texas and New 

 Mexico, and G. humilis, the California blind snake, in Arizona, 

 and southern California. They dig long tunnels in the earth 

 and feed on worms and insect larvae. 



Family BOID.E. PYTHONS and BOAS. The members of the 

 family BOID.E are constrictors. They live almost exclusively 

 upon birds and mammals which they squeeze to death in their 

 coils (Fig. 460). None of them is venomous and only a few are 

 large enough to be dangerous to man. The largest species on 

 record is the regal python, Python reticulatus, of Burma, which 

 attains a length of thirty feet. The anaconda or water boa, 

 Eunectes murinus, of South America averages about seventeen 

 feet in length. 



Not all of the BOID^E are large. Many of them are of moderate 

 size or even small. Four species are found in North America, 

 but they are comparatively rare and confined to the South- 



