235 
and conformation. Tliose 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 
formed the genera Vitrina^ Bulimus, Carocolla, Pupa, Scar a - 
bus, Succinea, Planorhis, Lymneus, Paludina, Ampularia, Me- 
lania, Janihina, Sigaretus, &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 Bigby 
introduced them into England for the benefit of the afflicted. 
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., ^^isan 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 e’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 
2 1 inches broad. 
* [Disseminator, Jan. 29, 1831. — Ed.] 
