GASTEROPODA. 



171 



Cylindrites. Lycett — Shell cylindrical; the spire 

 small, pointed, not always extending beyond the whorls, 

 which are numerous, flat, and separated by means of a 

 furrow ; the aperture is long, narrow, almost linear, with- 

 out a notch at the base ; the inner lip has at the base two 

 somewhat curved folds. — 6 species, fossil. 



Order VI. 

 PULMONATA. 



The animals of this extensive order breathe air through a 

 lung cavity, or have proper gills. They live on land, or 

 in fresh water, and have mostly a spiral shell. 



Family 1.— ONCIDIACEA. 



The bodies of these animals are naked, and are joined 

 in their entire length with the foot : they have gills close 

 to the lung cavity. They do not form a shell, and for 

 this reason the names of the genera alone will be given. 



Oncidium Buchanan ; Peronia Blain. ; Onchidella 

 Gray ; Buchannania Lesson ; Oris Risso, 



Family 2. -—LIMA CEA. 



The body of the animal is naked, or possesses only a 

 rudimentary inner shell, or a small one which covers only 

 part of the body ; the latter is joined in its whole length 

 with the foot ; there are four feelers generally, of which 

 two bear the eyes on the points. — All are terrestrial. 



