22 
J. HOPKIXSON-REMARKS 
and sometimes close to the surface of the water. Towards the end 
of autumn they have been observed to leave the vicinity of the 
water and expose themselves to the sun’s rays and drying winds, in 
order, it is supposed, to reduce the bulk of their bodies, which 
would otherwise be too large to be sufficiently withdrawn into their 
shells for full protection whilst they are hibernating. Our only 
species of Vitrina ( V. pellucida) has a body even still larger in 
proportion to the size of its shell, into which it can barely quite 
withdraw, but it is nevertheless one of the most hardy of our land 
mollusks, and almost the only one which roams about in severe 
winter weather, when it has frequently been observed crawling on 
the surface of the snow. It is seldom found far from water, and 
should be searched for in the vicinity of marshes and of running 
water, and in damp moss in woods as well as in exposed places. 
The Zonites are most frequently found under stones and pieces of 
wood which have been lying for a long time on the ground. The 
species are more difficult to distinguish from each other than those 
of any other genus, several of them being much alike, and this has 
led to many erroneous determinations. 
The Helices are very varied in their habits, and should be searched 
for in all the situations mentioned as being frequented by the land 
Mollusca generally. They affect dryer situations than Succinea and 
Vitrina, and are not so generally concealed from observation as the 
Zonites. Although the genus Helix comprises a large number 
of species, they are very dissimilar, and consequently easy to 
identify. 
Of the Bulimi one species is found almost exclusively near the 
sea, another buries itself in the earth or amongst decaying leaves, 
except in wet weather, when it sometimes climbs trees, and the third 
frequents rather exposed situations. 
The JPupce are most frequently found between the stones of 
loosely-built walls, &c., and amongst moss growing on walls and 
elsewhere. The species of the genus Vertigo differ only from those 
of Pupa in the lower pair of tentacles being absent, and in their 
shells being smaller, and of course their bodies also; they seem in 
fact to be miniature, partially-developed, forms of Pupa. They 
inhabit damper situations than the Pupce , and some of the species 
can only be obtained by wading in streams or marshes and collecting 
them from the stems of plants which, rising above the surface of the 
water, afford a habitation for these minute mollusks. 
Our only species of Balia, ( B . perversa) inhabits moss and lichens 
on old walls, &c. Of Clausilia, C. rugosa occurs most frequently in 
moss growing on trunks of fallen trees and on broken branches, and 
may also be found amongst almost any heap of stones, especially if 
containing a few chalk-flints. The other species frequent similar 
situations, but are not commonly met with. 
Of the two British species of Cochlicopa , C. lubrica attaches itself 
to the under surface of logs of wood and stones lying on the ground 
in exposed situations quite as frequently as in woods. The other 
species, C. tridens, occurs sparingly in woods. Our only species of 
