DECEMBER. 
341 
served them ; and I suppose^ as a fall of snow took place 
during the ensuing night_, most of those which remained active 
retired on that day. A few insects, however, are still to be 
met with ; I found a living Case-fly f Vhryganea ) on the 
surface of that snow I have mentioned, on the morning after 
it had fallen, and small Muscce and Tipulce still fly about 
the woods, and in sheltered situations. 
C. — Here are some hopping atoms, on the surface of the 
snow on the road side. I observe they are a minute species 
of Springtail, of a dark bluish grey colour. 
F, — This tribe of insects, the Springtails (Podura), 
minute and insignificant as they appear, have not been too 
mean to be the exclusive object of one instance of the in- 
ventive wisdom of the Deity. These little creatures have a 
mode of progression peculiarly their own, and differing widely 
from that of any other animal I know of. The tail termi- 
nates in two setse, or bristles, which are usually bent up 
under the belly, but when the insect wishes to move, these 
fly out straight, and by the elastic force, throw the insect 
forward by a vast leap. Whether the spring is kept bent by 
muscular effort, and flies out of itself when relaxed, or whe- 
ther its natural and unconstrained position is bent, and it is 
driven out by an exertion, I cannot affirm. It is singular 
that this species generally appears on the surface of snow, just 
after it has fallen ; whence coming, I know not. 
C. — I have observed several other species : one swarms 
on little pools of water in summer, sometimes so thickly as 
completely to hide the water, showing only a surface of black 
dust, resembling a parcel of gunpowder. Another, a little 
larger, and lighter in colour, abides in crevices of posts, and 
particularly of hot-bed frames, in spring. 
F, — ^The different modes by which locomotion is performed, 
constitute a very curious subject of investigation : they are 
far more varied than cursory observers would suppose. Some 
