•71 



genial. By means of its tiny foot, it will sometimes make the circuit 

 of the vivarium, before it selects a resting-place, which may be, even 

 then, but temporary. The species made its appearance in this district a 

 few years after the opening of the Gloucester and Berkeley canal, and 

 has increased in numbers to such an extent, that it may be said, with- 

 out exaggeration, to line the canal banks, from the edge of the water, 

 to a considerable depth, throughout its entire length of sixteen and a 

 half miles. Upon the dock walls at Gloucester, it appears to occupy 

 every available inch of space, from the water-line, to the depth of 

 fifteen or sixteen feet. 



Bulimus Lackhamensis has long been considered a local and com- 

 paratively rare species. I have reason to believe that it is neither, 

 and that its apparent rarity, is merely a consequence of the creature's 

 habits of life. 1 had frequently found the empty dead shell in many 

 places upon the Cotteswolds, where I could not meet with living speci- 

 mens, upon the most diligent search. In one of these, the most fre- 

 quently visited locality, towards the end of August, I was astonished 

 to find about a dozen upon the bole of a fine beech, near Birdlip, 

 apparently descending the trees. Upon the majority of the surround- 

 ing beech trees I discovered great numbers, in similar positions. In 

 the following month of March I found them again, in the same relative 

 position, but in the course of the next month could find none, where 

 they had been previously most abundant ; whence, I infer that the 

 apparent absence of the animal from its known habitats at certain 

 seasons, is attributable to its habit of spending the summer months 

 upon the trees, which it frequents at heights, which render it undis- 

 tinguishable. 



Limnaeus putris, on the desiccation of the herbage, consequent upon 

 the drying up of the rills whose banks it frequents, and which afibrd 

 the degree of moisture requisite for its sustenance, will, in very hot 

 weather, descend to the lower parts of the stems of the plants upon 

 which it feeds, whence it appears to follow the receding waters at a 

 certain distance. Should these entirely fail, and then become suddenly 

 renewed, as, for example, by heavy rains or the opening of sluices, it 

 immerses itself in them, and adopts for a length of time, proportioned 

 to that of its deprivation of the fluid, the habits of Lymnaeus. 



The various kinds of Lymnaeus are constantly seen floating on the 

 surface of the water with the foot, in the fashion of a boat, and the 

 shell downwards. They frequently do this, as may readily be seen, 

 for the purpose of supplying themselves with air, but, if watched 

 closelj', it will he found that they have also another object in view, 

 — they will be seen to collect upon the surface of the upturned foot. 



