REPTILIA 



391 



are the cobra of the East Indies where nearly 25,000 deaths 

 were caused by serpents in 1899 ; the vipers of Europe; the rattle- 

 snakes, water-moccasin, and copperhead of our own country. 

 There are twenty-seven poisonous species in this country of 

 which fifteen species are rattle-snakes. The venom serves the 

 snake both as a means of defense and of paralyzing its prey. 

 Some forms which are not poisonous assume bodily attitudes 

 similar to those of the poisonous species. The dangerous species 

 (and unfortunately the harmless ones) are being rapidly exter- 

 minated by man. 



Fig. 196. 



Rhamphorhynchus merensteri, — a restoration of an extinct flying Reptile. 

 Cambridge Natural History, after Geikie. 



From the 



Questions on the figure. — In what respects does a form like this dififer in 

 external appearance from a bird? From a bat? What skeletal structures would 

 a palaeontologist need to find in order to believe that an extinct form had the power 

 of flight? 



422. Special Exercises. — Find data concerning hibernation in reptiles and other 

 vertebrates: its object and advantages; preparation; place; degree in which vitality 

 is suspended during the process, etc. 



Describe the poison apparatus of venomous snakes. What is the homology 

 of the fang? Of the gland? 



How do different snakes capture their prey? How prepare it for swallowing? 



Describe and attempt to explain the motion of snakes from actual observation : 

 in water; on land. 



423. Reproduction and Development. — The ova escape from 

 the two ovaries into the body cavity. The ova enter the ovi- 

 ducts, and during the descent are fertilized. After fertilization 

 the glands in the walls of the oviducts add albumen and shell 

 structures, as in the birds. The eggs require a period of incu- 

 bation which usually occurs outside the body; though some 



