These insects closely resemble the previous tribe in general character,
to which also the same remarks nearly apply.
They are generally small insects, a length of a quarter of an inch
being considerably above the average. They are found commonly in loose
earth, under decaying leaves in woods, in moss, under the bark of dead
trees, and in rotten stumps. They always prefer damp situations.
[Illustration: Fig. 64.--Isotoma Gervaisi (Mag.)]
Cold seems to have but little effect upon them; they will recover their
activity after being frozen. One species, _Desoria glacialis_, is
found enjoying itself upon the Swiss glaciers, and another, _Degeeria
nivalis_, occurs upon the surface of snow in many parts of Europe. Some
species also may be met with hopping about upon the surface of standing
water. _Podura aquatica_, a minute blue-black species, is common in
such situations in England.
The five principal families are the _Smynthuridæ_, _Papyriidæ_,
_Degeeriadæ_, _Poduridæ_, and the _Amouridæ_.