258 



STJBKIKGDOM MOLLUSCA. 



escape, and, after swimming about for a time, attach them- 

 selves, and the pairs lay the foundation of a new colony. 



Fig. MS. 



IVustrafoliacea, Sea Mat. 



Some genera of Polyzoans possess singular processes 

 resembling a bird's beak, each cell having one and sometimes 

 two. These open and shut constantly, and if they are 

 touched with a needle, the mandibles will snap together upon 

 it so forcibly that the whole branch may be shaken by it. 



