194 ZOOLOGY 



at all depths and in water of temperatures of varying degrees. The 

 same species of sponge in different localities may assume very dififerent 

 shapes, the immediate surroundings acting upon the animal so as to change 

 its form. They appear to be protected from fish and other animals because 

 of their color and form, their skeleton, and an unpleasant odor. 



Reference Books 



for the pupil 



Herrick, Text-hook in General Zoology, Chap. VI. American Book Company. 

 Holder, Half Hours with the Lower Animals, Chap. II. American Book Company. 

 Jordan, Kellogg, and Heath, Animal Studies, Chap. IV. D. Appleton and Company. 



FOR THE TEACHER 



Miner, A Guide to the Sponge Alcove. Gmde Leaflet, No. 23. American Museunc 



of Natural History, New York. 

 Parker and Haswell, Text-book of Zoology. The Macmillan Company. 



