128 UNIVALVES. 



Genus SERPULA.*-PZwraZ. Serpula. 



CREEPER OR WORM SHELL. 



Generic Character. Shell univalve, tubular, 

 gradually tapering, usually adhering ; cavity 

 often interrupted by dissepimentsf at irregular 

 distances. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



These shells are usually found in very irregular 

 and diversified groups adhering to different 

 marine substances. They are invariably tubular, 

 and are either straight, or twisted; sometimes 

 they are isolated and detached, but are more fre- 

 quently found in clusters consisting of hundreds 

 of spiral tubes curiously interwoven ; they are 

 sometimes curled into a spiral form, but, differ 

 materially from the convoluted shells, as they 

 never have any regular numbers of whorls, or any 

 appearance indicating that this mollusk is directed 

 in forming these convolutions, by an invariable law. 

 The name is derived from the Latin serpo, I 

 cieep, and well designates their tortuousj vermi- 

 form appearance. There is very little known of 



* Plate VI. figures 2, 3, 



f Dissepiments are the partitions in multilocular shells : from 

 the Latin sepes, a hedge, and dis, a prefix signifying division. 



J Tortuous, from the Latin tort us twisted. 

 Vermiform, from vermis, a worm, and forma, a form. 



