35 
It very rarely happens that L. peregra retains an elongated 
form when it grows to any great size. A specimen of this 
shape I obtained in a pond near Flambro’ Head was considered 
so nnnsual that it was figured a short time ago in the Journal 
of Conchology. 
When the Ouse is let off, it is rather surprising to find that 
L. g^eregra swarms in certain parts. It lives here in quite deep 
water, but its ordinary habitat is a shallow pond. Under 
these unusual circumstances, although so plentiful, it is very 
poorly developed, indeed quite dwarfed. Some conditions 
seem favourable to the production of a number of individuals, 
but unfavourable to their development. 
From these remarks it will be seen that Pond-snails furnish 
us with abundant questions concerning their forms, just as the 
Hedge- snails supplied us with so many problems about their 
colours. Why the lip of the shell should become so widely 
expanded, and the spire so short under certain circumstances, 
and why, under other circumstances, the spire should become 
so elongated, and the mouth (comparatively speaking) so con¬ 
tracted—why, again, in some localites, we should find the 
spire as acute as a needle, and in others perfectly blunt, or 
even intorted—these, and the like, are questions which the 
modern school of science feels sure are worth investigation 
and have answers, because the great induction receives daily 
confirmation that no natural phenomenon is produced without 
an adequate natural cause. 
13 MAR 1886 
J. SOTHERAN, PRINTER, CONEY STREET, YORK. 
