158 



ZOOLOGY. 



Pig. 102. Nest of the Mygale. 



lined interiorly with' a kind of extremely consistent mortar, 



and a lid or covering i- 

 worked with alternating lay- 

 ers of miry earth and threads 

 reunited into a tissue, made 

 to fit exactly and to open 

 only outwards. The hingi- 

 supporting this covering is 

 formed by a continuation of 

 the filamentous layers pro- 

 ceeding from a point of its 

 contour upon the walls of the 

 tube situated beneath it, 

 forming there a pad or hood, 

 performing the office of a 

 mantle-tree. 



Among insects also may 

 be observed many remarkable instances of singular instincts 

 in the construction of dwellings. The larva of a small noc- 

 turnal butterfly, the tor- 

 trix vtriduiima,!* one of 

 these ; it lives on the oak, 

 rolling up its leaves and 

 connecting them together 

 with threads. Others, as 

 the teigne des draps, a 

 small grey and silvery 

 papillon or moth, which, 

 when in the larva state, 

 rapidly breaks up woollen 

 stuffs, forming galleries in 

 the thickness of the web 

 or cloth. With the hairs 

 or wool thus detached it forms long tubes as a dwelling ; 

 and what is singular, is, that when this becomes too small to 

 contain it, it breaks it open and adds to its length. 



Hybernating animals show singular instincts, tending to 

 their preservation : they prepare a winter dwelling, and shut 

 it in, as if conscious or aware that they would not require to 

 leave it for a long period; also to protect them from the access 

 of cold and enemies. This is the case with the marmot 

 exhibited in the street by Savoyard boys. 



325. A third class of instinctive faculties, which, like 

 the preceding, have a reference to the preservation of the 



Fig. 103. Nest of the Tortrir. 





