351 



The operculum of tlie (hell is corneous, permanent, 

 wrought with fine fpiral ridges, with a fmall knob in the 

 centre. 



The animal is of a pale colour, with two fetaceous 

 tentaciUa placed as ufual, and another fimilar one, fitu- 

 ated on the right fide, clofe to the head ; and near this, 

 on the middle of the hind head, is an appendage of a 

 mofl; elegant plumofe ftrufture, (like that of the animal 

 inhabiting Helix criflata,) very pellucid, extremely fen- 

 fible, and capable of inftantaneous retraftion: the eyes 

 are fituated on the head, at the bafe of the two anterior 

 tentacula. 



***REVERSED. 



J^nimal with the foramen on the leftjide. 



We haye thought it proper to make a feparate divi- 

 fion of the reverfed fhells of this genus, in order that 

 they might be brought together the better for compa- 

 rifon ; and perhaps it may not be improper in this place, 

 to define what is really intended by this term. 



Nothing appears more confufed and incomprehenfiblej 

 than the various defcriptions of different authors, con- 



cerninE^ 



