IV INTRODUCTION. 
few large non-venomous serpents. Depending so much upon small ver- 
tebrates and insects for food, the majority are important checks upon the 
increase of the enemies of garden and field. 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. Even 
the lizards that dart about on the bark, branches, and leaves in search 
of grubs, borers, and other pests of the orchard, are included in the gen- 
eral massacre. 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 habits 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; 
Ruizoponta, Crocodiles and Alligators; Sauria, Lizards; and Opurpia, 
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 fibro-cartilage between 
the ribs, near the margins. Among fresh water turtles, 7rionycide, this 
peculiarity is persistent; the upper shell, carapace, occupies only the central 
portion of the back, and the lower, plastron, is also incomplete. The Trunk- 
back, Sphargis, has a leathery case rather than a shell, The epiderm has 
ye 
