106 Transactions. 
Sphaerva are curiously gliding, and floating shell downwards ; 
while further up, where peaty linns look bottomless, and the pike 
gourmandises on everything he can get a hold of, with what a 
sense of victory you haul in your bag net and, letting the muddy 
water drip out of it, behold some new or rarely caught mollusk 
in the hey-day of his spirits, wondering with his blind but 
sensitive tentacles what in the world has come over the “ spirit of 
his dream” in the sunless depths where long-rooted pond-weeds 
spread their canopy of dusky green. 
There are several points with respect to the life-history of our 
mollusks worthy of careful and patient observation and record. 
For example, there is the controversy over Helix nemoralis and 
H. hortensis to settle. We could each add our quota to the eluci- 
dation of this vexed question were we to note whether these 
reputed species breed together, whether they at all seasons are 
found in one and the same locality, what their food is, what, in 
short, are their points of resemblance and of distinction. In 
carrying out the practical study of our L. and F. W. mollusks, 
it is always well to note down, at the time of capture, what is 
the plant they appear attached to, and, when coming indoors, 
preparatory to killing your specimens in boiling, literally boveng, 
water—the only merciful and instantaneous method of disposing 
of them—to note particularly the general colour of the body, the 
surface-texture of the back, and the shape of tentacles and “foot,” 
with an approximate indication of their length as compared with 
the length or diameter of their shells. After leaving your 
mollusks for a few hours in the water, a little neat and skilful 
manipulation with a bent pin will, in nearly all cases, fetch out 
the soft parts, leaving you with a shell more or less clear, but 
always worth reverent examination, and revealing, under the 
lens, curves of sculptured traceries and hues prismatic to an 
amazing degree. Think for a moment of what has yet to be done 
in ascertaining the causes of variation in species, sub-species, and 
variety. There are certain species like Limnaea peregra, whose 
capacity for variation in shell form is something astonishing. 
We could—or we may some day at any rate—arrive at a clue 
which will help us in threading out towards the truth a path 
through the labyrinths of these seemingly lawless creatures— 
absolute Robin Hoods of the submerged forests of our tarns and 
streams—if the facts of their lives and their general surroundings 
were only narrowly and well watched. 
