226 



ZOOLOGY 



Group of acorn barnacles (closed), with starfish 

 moving over the mass. Each shell contains a 

 fixed, degenerate crustacean. 



attached to the body of the 

 crab. Others attach them- 

 selves to fishes and are known 

 to fishermen as fish Hce. 



Characters Common to 

 all Crustaceans. — In spite 

 of all the differences in 

 structure found in the va- 

 rious crustaceans studied, 

 there are a number of char- 

 acters possessed by all 

 crustaceans in common. 

 They have a segmented 

 body covered with an exo- 

 skeleton; the latter con- 

 tains chitin and carbonate of lime. The body is bilaterally sym- 

 metrical (except in the hermit crab). The appendages are jointed 

 and branched. Two pairs of antennae are present. The eyes are 

 stalked and compound. Crustaceans breathe by means of gills 

 and are mostly aquatic. 



Reference Books 

 for the pupil 



Burnet, School Zoology, pages 67-73. American Book Company. 



Davison, Practical Zoology, pages 133-141. American Book Company. 



Herrick, Text-book in General Zoology, Chap. XIII. American Book Company. 



Jordan, Kellogg, and Heath, Animal Studies, Chap. IX. D. Appleton and Com- 

 pany. 



Hunter and Valentine, Laboratory Manual of Biology, pages 138-146. Henry Holt 

 and Company. 



FOR THE TEACHER 



Herrick, The American Lobster. Report of U.S. Fish Commission, 1895. 



Parker, Elementary Biology. The Macmillan Company. 



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



