OF NATURAL HISTORY. 143 



ving. When it pleafes, it can loofen the bafe of the cone by •which 

 it is attached to the rock, reverfe its body, and employ the filaments 

 round its mouth as fo many limbs. Still, however, its movements 

 are imperceptibly flow. For thefe fads feveral authors might be 

 quoted ; but we fhall refer the reader folely to M. de Bonnet *. 



Before we conclude this chapter, we iTiall juft mention a mode of 

 flying which is peculiar to certain infeds. The viajon-bee, which is 

 one of the folitary fpecies, has received that appellation, becaufe it 

 conftruds a neft with mud or mortar. Externally, this neft has no 

 regular appearance ; and is, therefore, generally regarded as a piece 

 of dirt accidentally adhering to a wall. This habitation, however 

 unfeemly in its exterior afped. Is furniflied with regular cells, and 

 often gives rife to great conflids. When the real proprietor is 

 abroad in queft of materlals'to finifh the neft, a ftranger takes pof- 

 feflTion. At meeting, a battle always enfues. This battle is fought 

 In the air. Sometimes they fly with fuch rapidity and force againft 

 each other, that both parties fall to the ground. But, in general, 

 like birds of prey, the one endeavours to rife above the other, and 

 to give a downward blow. To avoid the ftroke, the undermoft, 

 inftead of flying forward or laterally. Is frequently obferved to fly 

 backward. This retrograde flight is likewife performed occafionally 

 by the common houfe-fly, and fome other infeds, though we are 

 unable to perceive what ftimulates them to employ this uncommon 

 movement. 



C H A P5 



* Oeuvres de Bonnet, 4to edit. torn. 5. pag. 345. 



