THE VERTEBRATE ANIMALS 297 



relationship to birds in that their large eggs are incased in a leath- 

 ery, limy shell. 



CLASSIFICATION OF REPTILES 



ORDER I. Chelonia (turtles and tortoises). Flattened reptiles with body inclosed 

 in bony case. No teeth or sternum (breastbone). Examples : snapping 

 turtle, box tortoise. 



ORDER II. Lacertilia (lizards). Body covered with scales, usually having two- 

 paired appendages. Breathe by lungs. Examples: fence lizard, horned toad. 



ORDER III. Ophidia (snakes). Body elongated, covered with scales. No limbs 

 present. Examples : garter snake, rattlesnake. 



ORDER IV. Crocodilia. Fresh-water reptiles with elongated body and bony scales 

 on skin. Two paired limbs. Examples : alligator, crocodile. 



REFERENCE BOOKS 

 ELEMENTARY 



Davison, Practical Zoology, pages 211-226. American Book Company. 



Ditmars, The Reptiles of New York. Guide Leaflet 20, American Museum of Natural 



History. 



Herrick, Textbook in General Zodlogy, Chap. XXI. American Book Company. 

 Jordan, Kellogg, and Heath, Animal Studies, Chap. XVI. D. Appleton and 



Company. 



ADVANCED 



Ditmars, The Reptile Book. Doubleday, Page, and Company. 

 Parker and Haswell, Textbook of Zoology. The Macmillan Company. 

 Riverside Natural History. Houghton, Mifflin, and Company. 



Birds 



Problem XXXIX. Study of some adaptations in and re- 

 actions of birds. (Laboratory Manual, Prob. JCXXIX?) 



Adaptations. Birds among all other animals are known by 

 their covering of feathers and the peculiar modification of the fore 

 limbs for flight. In no other group of animals may we study 

 adaptations so well as here. 



Field Work. Bird activities may best be studied out of doors. Any 

 city park offers more or less opportunity for such study, for several of 

 our native birds make the parks their home. If not these, then the Eng- 

 lish sparrow can be found anywhere in the East. The best time for 

 making observations is early in the morning, especially in the spring 



Body. The body of a bird, under its covering of feathers, is 

 rounded and more or less pointed at each end. Powerful muscles, 



