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little adapted for working, though its industry yields in 
nothing to that of the other araneides, but even exceeds it. 
It was necessary, therefore, that nature should supply it with 
other instruments. These reflections led M. Latreille to a very 
attentive examination of the organs of these animals, and he 
discovered, above their mandibles, some hard, corneous points, 
the anterior of which, ranged in a transverse series, resemble 
a sort of rake. Without seeing these animals in the per- 
formance of their operations, it could scarcely admit of doubt 
that this peculiar instrument must be very useful to them for 
the formation of their nest. 
In so carefully concealing their retreat, in preparing and 
constructing it with so much art, these araneides have less in 
view their own preservation than that of their offspring. 
Rossi has found in the nest of that species, which he names 
Aranea sauvagesti, its numerous family. These two species 
( cementaria and sauvagesiij excavate, in argillaceous soils, 
a burrow, or cylindrical trench, having the same diameter 
throughout. Its relative dimensions may vary according to 
the species and the age of the animal. It usually chooses 
soils in declivity, or cut vertically, so that it may not be 
stopped by the rains, and which besides are arid, and com- 
posed of a strong earth, without any mixture of pebbles or 
small stones. It takes care to unite the interior walls of its 
habitation, and to line them with a silken pellicle, so as to 
consolidate them, and prevent any fallings in. This web may 
also contribute to the facility of its movements, and advertise 
it, by the motions which it undergoes, of what is passing at 
the entrance. A door, or sort of flat trap, but tolerably thick, 
circular, composed of diff erent beds of earth, moistened and 
bound together with silk, smooth, a little convex, covered with 
very strong threads, forming a very close tissue underneath, 
closes the aperture of this burrow. The threads with which 
the interior surface of this door is lined, are prolonged from 
