REPTILES. 



325 



grooved or channelled, or only the hinder teeth grooved ; not poisonous. 

 The PeropODA, with rudimentary hinder limbs, includes the Pythons.^ giant 

 snakes of Africa, and Boa and Eunectes (the anaconda), equally large forms, 

 from South America. The AGLYPHODONTA resemble the Peropoda 

 in the absence of grooved teeth, but differ in the absence of limbs. The 

 species are numerous ; our species mostly belong to the Colubrid^, in 

 which the head is distinct from the trunk ; the teeth are numerous on max- 

 illaries and palatines. Over 700 species described ; about 50 in north- 

 eastern U.S. Tropidonotas includes our water-snakes ; our garter-snakes 

 belong to Eutainia. Bascanion contains the black snakes ; Heterodon, 

 the choleric but harmless spreading vipers. Rachiodon of Africa has the 

 vertebral hypapophyses tipped with enamel, 

 forming a series of teeth which penetrate 

 the oesophagus, and are of use in cutting 

 open the eggs on which these animals feed. 

 The Opisthoglypha have some of the 

 posterior maxillary teeth grooved. Dipsas 

 and its allies are tropical arboreal forms, 

 with nocturnal habits. 



Section II. PROTEROGLYPHA. 

 Snakes with large, permanently erect, 

 grooved poison fangs on the anterior end 

 of the maxillaries. A poison gland is al- 

 ways present. They live in warm countries, 

 and are usually brightly colored (warning 

 colors). The Elapid^ contains the coral- 

 snake or bead-snake, Elaps fulvus, of our 

 southern states ; Naja tripudians, the 

 cobra of India; and N. haje, the asp, tra- 

 ditionally connected with Cleopatra. The 

 HYDROPHID.E embraces the sea-snakes of 

 the Indian Ocean, one species ranging to 

 Panama. These are pelagic throughout 

 life, feeding upon invertebrates and small 

 fishes. They bring forth their young 

 alive. 



Section III. SOLENOGLYPHA. Maxilla vertical, in front armed 

 with large erectile poison fangs in which the groove has been converted by 

 folding into a tube. In the V1PERID.E there is no pit or groove between 

 nostril and eye. The species, about 20 in number, all belong to the old 

 world, two species of vipers {Viperd) and one adder (Pelias) occurring in 

 Europe. In the Crotalid^, the 40 species of which occur in America 

 and Asia, there is a deep pit, partly occupying a cavity in the maxillary 

 bone, between nostril and orbit. Crotalus, in which the tail ends in a 

 rattle formed by the remains of exuviated skin, contains the rattlesnakes, of 



Fig. 320. A, poison tooth 

 of rattlesnake ; C, the same in 

 section (solenoglyphic); i?, sec- 

 tion of poison tooth of the 

 cobra (proteroglyphic), show- 

 ing the groove (^) of closure in 

 formation of the poison canal, 

 c ; 0, openings of poison canal ; 

 p, pulp cavity ; after Boas. 



