MALACOLOGY. 



changed? Which is the THIRD SUB-KINGDOM? What is said of their ex 

 ternal form? Of the internal parts? What of the nervous system? Of 

 their organs of sense ? To what are the muscles attached ? How are the 

 animals enabled to crawl, swim, &c. ? Why are their motions very slow? 

 What is said of the organs of respiration ? Of the blood, stomach, c. ? 

 What is meant by the mantle ? How does it vary ? How is the skin in 

 many Mollusks protected ? Is the shell always external ? Wl at are those 

 called which have no shell? What those which have a shell? How is the 

 shape of the shell determined? Whence the divisions into UNIVALVES and 

 Bivalves ? What other names have these divisions received? What is 

 said of them ? What is said of the coloring of shells ? Name the parts of 

 a Univalve Shell, &c. Give the explanation of Bivalve shells as furnished 

 by the text and Plate XVII? What are fixed shells? What are free 

 shells ? What other division of the Mollusks are given ? What is said of 

 the adaptation of the shell and habits of Mollusks to their respective situa 

 tions ? In what climate are they most abundant and most brilliantly col 

 ored? What is said of the number of species? 



