464 SUPPLEMENT 



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 sauvagesii, its numerous family. These two species 

 (cementaria and sauvagesii) 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 different 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 



