xin BACKBONED ANIMALS 285 



the zebra, outwrestle the athlete, and crush the tiger.' 

 It is a Divine hieroglyph of the demoniac power of the 

 earth of the entire earthly nature. As the bird is the 

 clothed power of the air, so this is the clothed power of the 

 dust ; as the bird is the symbol of the spirit of life, so 

 this of the grasp and sting of death." 1 



This well-known and eloquent passage is not abso- 

 lutely accurate thus the serpent breathes not scarcely 

 but strongly with its one lung but it is full of true 

 insight into the nature of serpents, and it is an apprecia- 

 tion of beauty in types which most people regard with 

 prejudice. 



A few snakes have mouths which do not distend, skull 

 bones which are slightly movable, teeth in one jaw 

 (upper or lower) only, and rudiments of hind legs. These 

 are included in the genera Typhlops and Anomalepsis, 

 and are small simple ophidians. 



Many are likewise non-venomous snakes, but with 

 wider gape and more mobile skull bones, and with simple 

 teeth on both jaws. Some are very large and have 

 great powers of strangling. Such are the Pythons, the 

 Boa, and the Anaconda. To these the grass snake 

 (Tropidonotus natrix) is allied. 



Many poisonous snakes have large permanently erect 

 grooved fangs in the upper jaw, and a salivary gland whose 

 secretion is venomous. Such are the cobra (Naja tripu- 

 dians), the Egyptian asp (Naja haje), the coral snakes 

 (Elaps), and the sea snakes (Hydrophis). 



Other poisonous snakes have perforated fang teeth, 

 which can be raised and depressed. Such are the vipers 

 ( Vipera), the British adder (Pelias berus), the copperhead 

 (Ancistrodon contortrix), the rattlesnakes (Crotalus). 



Tortoises and Turtles (Chelonia). Boxed in by a bony 

 shield above and by a bony shield below, and often with 

 partially retractile head and tail and legs, the Chelonians 

 are thoroughly armoured. On the average the pitch of 

 their life is low, but their tenacity of life is great. Slow 

 in growth, slow in movement, slow even in reproduction 

 are many of them, and they can endure long fasting. 



1 Ruskin's Queen of the Air. 



