SERPULA. Ill 



The concameratecl varieties which are found 

 among the Serpuls do not deserve a separate di- 

 vision, because the conformation appears to ori- 

 ginate not in any specific diiference, but in an in- 

 stinctive desire of the animal, for some important 

 purpose, to increase the length of the shell without 

 materially adding to the size of his apartment. 

 The chambers are not connected with each other 

 by any siphunculus or opening ; the last can there- 

 fore only be inhabited. No sign of the internal 

 dissepiments is visible externally, except in one 

 species, S. Polylhalamia. 



In this genus as well as in the preceding one, 

 the animal has been supposed to live with little or 

 no adhesion to his shell ; but the degree and mode 

 of his attachment are doubtless as various as the 

 peculiar specific forms. 



The creeping, tortuous character of the first di- 

 vision of Serpula furnishes us with a clue to the 

 etymon of the generic name, to spTrw, Serpo. 



