156 ELEMENTS OF COMPARATIVE ZOOLOGY. 



large colonies, the members of which are more or less inti- 

 mately connected with each other. In some cases the ani- 

 mals resulting from budding produce eggs, and these eggs 

 grow into forms unlike their parents but like those from 

 which the parents were budded. In other words, the child 

 does not resemble the parents, but the grandparents. 

 This peculiarity is called "alternation of generations." 



The tunicates are all marine, and they abound in the 

 seas of all parts of the world. Some of them are known 

 from their shapes and color as " sea-peaches," others as 

 "sea-pears," while a common name for all is "sea-squirts," 

 due to the fact that they squirt water from the openings 

 upon being disturbed. 



BRANCH III. VERTEBRATA (p. 127). 



