300 VERTEBRATES: REPTILES. 



dry places, and spends much of the time in the ground. 

 The vertebras of the tail are so easily separated, that it is 

 broken by a very slight blow ; and this fragility of the 

 tail has gained for this animal its popular name. 



The Genus Anguis contains the Blind-Worms. 



The Common Blind- Worm, A.fragilis, of Europe, is 

 over a foot long, silvery yellow above, blackish beneath. 



The Genus Amphisbcena, comprising the Double Walk- 

 ers, has the head and body nearly of uniform size, a 

 form which enables them to move backwards or forwards 

 with equal facility. They inhabit the hot regions of Soulh 

 America. 



The Genus Typhlops comprises reptiles that externally 

 resemble earth-worms. They are found in the hot regions 

 of both continents. The eye is a mere point, and scarcely 

 visible through the skin. 



SUB-SECTION III. 



THE ORDER OF OPHIDIA, OR SERPENTS. 



THE Order of Ophidia comprises scaly reptiles which 

 are exceedingly long, and without feet, and which move 

 by the alternate folds of their long and slender body. 

 The ribs and vertebrae make up most of the skeleton, the 

 sternum being wholly wanting. The vertebrae join each 

 other as a ball and socket joint, thus giving great free- 

 dom of motion. The bones of the jaws and mouth, which 

 in the higher animals are more or less firmly united, are 

 connected in animals of this order only by extensible 

 ligaments, an arrangement by which the mouth may 

 be distended so as to receive, an object of much greater 

 diameter than the serpent itself. Both the jaws and pala- 

 tine arches are almost always armed with teeth. These 

 are solid, and situated on the margins of the maxillary 

 bones. As serpents do not masticate their food, their 



