110 
the peristome being covered with a thin reflexed portion of the 
mantle. I at first considered it was a modification of the genus Na- 
nina with a more dilated mantle, and a much more globular shell ; 
but on more particular examination, I am convinced that it is the 
type of a new genus, as the back of the foot is depressed and flat- 
tened, and quite destitute of any appearance of a subcaudal gland. 
I propose to call this genus Pfeifferia, after my excellent friend 
Dr. Louis Pfeiffer, the author of the “‘ Monographia Helicum ;”’ it 
may be characterized as follows :— 
PYEIFFERIA. 
Animal large for the size of the shell; mantle edge expanded, thin, 
reflexed over the outer surface of the shell when contracted in spirits, 
forming an even margin to the outer part of the peristome. Foot 
moderate, depressed behind, acute at the tips, without any subcaudal 
gland. Shell subglobose, imperforate, thin, brittle, white, pellucid. 
Spire with small whorls, third and fourth rapidly enlarging, the last 
inflated; aperture rounded, lunate. Columella slightly and regu- 
larly arched. The peristome thin, straight, acute. 
Mr. Cuming informs me, that when he poured boiling water on 
them, to kill them, the animal, in attempting to return within 
the shell, burst it, from being so much larger than the shell itself ; 
he was consequently compelled to drown the animal and let it re- 
main in the water until it was half putrid, by which means he was 
able to procure sound shells. He tried boiling water several times, 
and destroyed some hundreds of shells before resorting to the latter 
means. 
I may observe, that the animal in spirits does not give one the im- 
pression of being so large, compared with the shell, as the above 
description would imply ; but, like the Succinee, Vitrine and other 
genera, these animals appear to have the faculty of absorbing a quan- 
tity of moisture, and of inflating their bodies and making them appear 
of a large size, and when suddenly killed they have not the power of 
lessening it, but while alive they certainly have. During dry and 
perhaps cold weather they expel the air and water, and so contract 
their bodies, that they can be withdrawn a considerable distance 
within the cavity of the shell. I have often seen this ceconomy in 
the amber snails, Succinee, and the shield shells, Vitrine, and Pro- 
fessor Nilsson has observed the same fact with regard to the latter 
genus, as quoted by me (Gray, Turton Man. 119). 
The type of the genus is 
PFEIFFERIA MICANS. 
Helix micans, Pfeiffer, Proc. Zool. Soc. 1845, 71 ; Monogr. Helic. 
li. 24. 
Corasia micans, Albers, Heliceen, 111. 
Nanina Albaiensis, Gray, Ann. & Mag. Nat. Hist. xii. 1853, p. 331, 
teeth. 
Hab. Lucon. 
