MOTIONS OF INSECTS. 365 



they return from their more distant excursions during 

 the autumn, may with more certainty be referred to 

 this cause. White says, they rendezvous by thou- 

 sands over Selborne Down, wheeUng round and 

 diving in a playful manner in the air, and when this 

 ceremony is over, with the last gleam of light, they 

 retire to the deep beech woods of Tisted and Kepley. 

 It may not be improper, however, to distinguish be- 

 tween this and the restless tossing about and flapping 

 of the wings, often exhibited by rooks previous to a 

 storm, which more usually occurs in the morning, and 

 closely resembles the tossing of sea-birds on the bil- 

 lows during a gale.* 



The quickness of the vision of tipulidan gnats, and 

 the rapidity as well as the dexterity of their motion, 

 may be considered not a little remarkable, from the 

 circumstance of their flying unwetted in a heavy 

 shower of rain, whose drops — bigger than their own 

 bodies — if they fell upon them, must dash them to the 

 ground ;f unless it may be that the drops glide olf 

 their wings as they do off" the feathers of a duck, while 

 the elasticity of their bodies may save them from ac- 

 cidents, even when they chance to be pelted. 



A very pretty species of these choral flies (Chiro- 

 nomus aterrimiis, Meigen) is exceedingly common 

 in the vicinity of London, appearing about the close 

 of winter, and readily distinguished by its shining 

 snow-white wings, rendered more conspicuous by the 

 contrast of its black body, while the male has his 

 antennae adorned with beautiful lead-grey plumelets. 

 Though groups of these may be found sporting on 

 the borders of woods and near water, even in January, 

 proving that, though not half the size of the common 

 gnat {Cu!ei pipiens), they can brave the bleak winds 

 of winter, — yet they often crowd into our apartments, 

 like many others of the family. We have just been 

 * J. R. f Kiiuy and Spence, vol. ii. p. 374. 



