348 HELICINAD^. 



CYCL0ST05IA DENTATUM, Say. 



Plate LXII. 



C. testa conico-cylindracea, detruncata, sub-perforata, 

 concinne cancellata, ex flavo rufescente, ssepe rufo inter- 

 ruptim fasciata ; anfractibus quatuor, convexis ; sutura 

 fimbriata ; apertura orbiculata, postice angulata ; labro 

 reflexiiisculo, albo. 



SYNONYMS AND KEFERENCES. 



Cydostoma clentatam, Say, Journ. Acad. Nat. Sc. V. 125, Aug. 1S25. 

 De Kay, New York Fauna, p. 82. 



DESCRIPTION. 



Aotmal. Body very short, pale, tentacles darker, 

 slender, somewliat enlarged at tij^s ; eyes black, promi- 

 nent, situated on a tubercle at the external base of the 

 tentacles. Proboscis bifurcate, the two points serving 

 the purpose of buccal tentacles. Operculum horny, the 

 spiral of about two and a half turns. 



The shell is carried somewhat laterally, and very little 

 elevated. The motions of the animal are very rapid ; 

 the locomotive disk contracts in an undulatory manner ; 

 and when the animal has advanced so that the shell 

 drags along by its side, by a sudden contraction of the 

 neck the tip of the shell is suddenly jerked forward, so 

 as to bring the shell at right angles with it; and this 

 movement, in a quarter of a circle, is very rapidly per- 

 formed. As the operculum prevents the animal, when 



