UNIVALVES SERPULA. 193 



SERPULA Worm-Shell. 



DESCRIPTION OF PLATE XXXIV. 



Div. I — Fig;. 4. S. contortuplicata. Dnr. II — Fig. 2. S. anguina. 



Div. II Fig. 1. S. lumbricalis. Div. II.— Fig. 5. S. retorta. 



Div. III. — Fig. 3. S. aquaria. 



Shell univalve, tubular, generally adhering to other substances. 



THE construction of the Serpulse is extremely irre- 

 gular, and the groups they form are no less diversified. 

 They are invariably tubular, and sometimes present 

 themselves detached, either straight or twisted, but 

 more frequently in clusters spirally entwined, adher- 

 ing- to a variety of other substances. 



The colors of the Serpulse are generally brown, pur- 

 ple, yellow, tawny, pink, or white, and sometimes tinged 

 with green. Of the species which are attached to extra- 

 neous substances and form the first division, some are 

 isolated and others collected into large masses, contain- 

 ing many hundred spiral and twisted tubes, curiously 

 interwoven : the shells of the former class have their 

 whorls nearly contiguous, and resemble some of the 

 Helices: such are the S. spirillum and S.spirorbis. 

 The S. vermicularis is an illustrative example of the 

 aggregated species. 



The second division has also its isolated and ag-eTe- 

 gated species ; to the former belong the S. protensa and 

 S. lumbricalis, which is a flexuous shell, with a spiral 

 O 



