235 



and conformation. Those that reside on the land and respire air 

 only by means of a spiracle leading to a cavity for respiration, 

 lined with a plexus of pulmonary vessels, were associated with 

 such as reside wholly in the water, and with others that are am- 

 phibious, as unlike in their external character as in their anatomi- 

 cal structure. It was in reality a great reservoir for Molluscous 

 animals that correspond in some general appearances, all of which 

 his generic definition, however comprehensive, could not include. 

 The present more natural condition of this group is owing to the 

 successive improvements of Brugui^re, Draparnaud, Lamarck and 

 Montfort, who removed from it various species, of which they 

 ibrmed the genera Vitrina, Bulimus, Carocolla, Pupa,. Scara- 

 7ms, Succinea, Planorbis, Lymneus, Pahidina, Ampularia, Me- 

 Jania, Jantliina, SigareUis, &c. Many of these Ferussac has 

 again restored to the genus Helix, forming various subgenera under 

 new names which he has applied to them. Lamarck, as he has 

 limited the genus, describes one hundred and seven species of his 

 own collection ; but Ferussac, whose boundaries are more compre- 

 hensive, being founded on the characters of the animal, enumer- 

 ates five hundred and forty-four. 



To a species of this genus, common to Europe and a part of 

 North America, the H. aspersa, Muller, sanative qualities were 

 formerly attributed in diseases of the lungs, and Sir Kenelm Digby 

 introduced them into England for the benefit of the aflSicted. 

 Many species are served upon the tables of the luxurious, and 

 amongst the Romans the breeding and fattening them for food 

 was a particular occupation. Montfort informs us that the H. 

 pomatia, Linn., " is an object of commerce; at Paris, Vienna, 

 Rochelle, in Switzerland, &c., they are taken to market, and are 

 exported in barrels to the Antilles ;" he adds '* c'est un aliment 

 sain, succulent et prolific." 



Lamarck's genus Carocolla is much like Helix, but the volu- 

 tions are always acutely angulated. In Bulimus the aperture is 

 longer than wide, and in Pupa, Clausilia, &c., the form is cylin- 

 drical, and the labia are continuous. 



Anodonta imbecillis.* Since the publication of the des- 

 cription of this species, Mr. 0. Evans has presented me with a 

 much larger specimen. It maintains its proportions, and is nearly 

 2i inches broad. 



♦[Disseminator, Jan. 29, 1831.— Ed.] 



