156 



POPULAR CONCHOLOGY. 



remain stationary by day, yet when disturbed they will 

 creep away with a slow and equal pace ; sometimes sliding 

 sideways and creeping under rocks and stones for conceal- 

 ment. If accidentally removed, they soon recover their 

 position by violently contorting and undulating ; and for 

 defence they sometimes roll themselves up like woodlice." * 



Nototrema. Rafinesque. — Shell consisting of three 

 separate pieces; the first or middle one is large, oval, 

 conical, bored through at the point ; the second is small, 

 lateral, placed beneath, serving for support ; the third is 

 operculum-like, closing up the point of the first. Animal 

 adhering firmly in the manner of a Patella; the head 

 lengthened, and truncated ; the eyes sessile. — A very 

 doubtful genus. 



Order IV. 



CIRRIBRANCHIATA. 



The animals have the organs of breathing hair-like, and 

 situated in two lobes above the neck ; the foot 

 is formed like a proboscis, pointed and conical ; 

 shell tubular, symmetrical, slightly curved, and 

 open at both ends. — Marine. 



Dentalium. Lin. — Shell tubular, regular, 

 smooth or fluted, sometimes with a cleft ; more 

 or less curved in form, gradually tapering to 

 the posterior end ; both extremities open. Ani- 

 mal long, slender, attached to the shell near 

 its hinder extremity, having a rudimentary e feSS*. 



* Swainson's Malacology. 



