IV IXTRODUCTIOX. 



few large non-vciiumous serpents. Depending so much upon small \'er- 

 tebrates and insects fur food, the majority are important checks upon the 

 increase of the enemies of garden and tield. Occasionally farmers recog- 

 nize the compensation received for protecting and gathering these despised 

 creatures; more often, unfortunately, in prejudice and ignorance of the 

 friendly habits, they exert themselves in favor of extermination. E^■en 

 the lizards that dart abuut on the bark, branches, and leaves in search 

 of grubs, borers, and other pests of the orchard, are included in the gen- 

 eral massacx'e. The dangerous serpents of the United States are the 

 Rattlesnake, the Moccasin, and Copperhead, and, though the error is on 

 the side of safety, the popular fear of these is much greater than is ■war- 

 ranted by fact. 



The flesh of most of the Turtles, many of the Lizards, and that of 

 numerous Batrachians, is excellent for the table. Aside from their Value 

 on account of flesh and hal)its of feeding, the Batrachia form an item of 

 food for fishes that is not to be overlooked by those engaged in stocking 

 ponds and streams. 



Reptiles. 



There is a great number of Reptiles among the fossils. Some of these 

 belong to recent genera; others are of enormous size, and pertain to genera 

 long ago extinct. It is the purpose, however, to confine attention in this 

 work to living forms, and in the main to such as now exist in North 

 America. These are included in four orders: Testudinata, Turtles; 

 Rhizodonta, Crocodiles and Alligators; Sauria, Lizards; and Ophipia, 

 Serpents. 



Testudinata. 

 The form typical of this order has a short, clumsy body, of which the 

 vital portions are inclosed in a bony case, formed by the expansion and 

 consolidation of the backbones, ribs, and sternum. Perhaps it might be 

 more exact to say the shell or box is formed by a union of dermal and neural 

 skeletons. Young turtles have spaces covered by fibi'o-cartilage between 

 the riljs, near the margins. Among fresh water turilcs, ■ Trionycidce, this 

 peculiarity is persistent; the upper shell, carapace, occupies only the central 

 portion of the back, and the lower, 'plastron, is also incom{)lete. The Trunk- 

 back, Spharr/h, has a leathery case rather than a shell. The epiderm has 



