615 
weather, the threadlike branches of the potamogeton and hypnum, by 
collapsing would squeeze out the air from the nest, were its walls 
not made sufficiently strong to resist the pressure ; hence the 
selection of chcira, which from tho lime it contains is strong 
enough to afford resistance, and oddly enough is the only plant to 
bo found there which would answer the purpose. From careful 
examination which I made, it was clear that in many instances 
tho spiders would have to travel considerable distances to find tho 
suitable material for building; but as a rule they were most nu- 
merous in tho places where tho churn flourished. — J. Lowe, M.D. 
On the habits of the larva of the Tiger Beetle ( Cicindela 
cmnpestris). The larval form of this beautiful beetle exhibits 
the same rapacious habits as the adult, with this difference, that 
while the latter takes its prey by its greater activity and strength, 
the former, inhabiting as it does a burrow on the ground, has to 
resort to stratagem not less remarkable than that of the ant-lion. 
Their habitat may be readily found on the commons or sandy 
places frequented by the adult beetles. A small opening in the 
ground surrounded by particles of sand thrown to a distance at once 
discloses tho abode of this singular creature. Having kept some 
of them in confinement and observed their habits, a short sketch 
of these may be worth recording. The head is broad and flat, 
furnished with a very strong and sharp pair of mandibles, posterior 
to which is a slight depression covered with a glutinous secretion 
which is the bait by which flies are attracted, when the larva or 
rather the trap is set. The feet are turned backwards to render 
the ascent and descent of the creature more easy in its burrow. 
In excavating the burrow which is generally perpendicular, tho 
jaws are used to scoop out the soil which is carried on the top of 
the head to the surface of the ground, and then by a sharp jerk 
projected to a distance, sometimes of several inches. 
In capturing its prey, the larva raises its head to the opening of 
its burrow, which it accurately fits, throws out a little of the 
glutinous secretion on the surface of the head, and awaits the 
approach of a fly or other insect. The moment the head is 
touched, an audible snap of the jaws shows that the victim is 
secured, and the larva at once descends into his lair to consume it. 
They arc by no means particular in the choice of food. I found 
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