144 UNIVALVES. — SERPULA. 



SERPULA— Worm-Shell. 



Animal — a Terehella: Shell univalve, tuhular, generally 

 adhering to other substances : often separated intej'nally 

 hy divisions at uncertain distances. 



THE genus Serpula contains forty species ; their form 

 (with few exceptions) is exceedingly irregular. They are 

 generally found in groups or clusters, adhering to other 

 substances, such as rocks, stones, roots of trees, sides of 

 ships, zoophytes, sertularise, fuci, shells, corals, &c. They 

 are invariably tubular, and present themselves sometimes 

 isolated, either straight or twisted, but more frequently in 

 clusters, consisting of many hundred spiral and twisted 

 tubes, curiously interwoven with each other. 



Of the species which are isolated and spiral, may be in- 

 stanced the S. spirillum, S. spirorbis, and S. afra; which 

 have their whirls nearly contiguous, and resemble the He- 

 lices. 



To this same class belongs the well-known but rare shell, 

 the Watering-pot Serpula, (S. aquaria). Its larger end is 

 closed by a convex disk, with numerous small perforations, 

 and generally a longitudinal one in the middle, the whole 

 encircled by a dilated margin of elegant papyraceous tubes, 

 resembling a beautifully plaited ruff or frill; the smaller 

 end is open. It is found in the Indian ocean, and seldom 

 exceeds five inches in length. 



The S. gigantea is about an inch in diameter, and some- 

 times exceeds half a foot in length. The S. lumbricalis is 

 a flexuous shell, with a spiral acute tip, and very much re- 

 sembles a cork-screw. 



One of the remarkable species of this genus is the S. 

 anguina, which has a slit or long-jointed cleft along the 



