VARIETIES. 321 



wholly destroyed. The ground was then ploughed, and 

 immense swarms of sparrows came and devoured the larvce as 

 the plough turned them up ; it was then cropped with potatoes, 

 and the Tipula disappeared. The clayey part of the field, to 

 the very limit of the sand, entirely escaped the devastation ; 

 thus, apparently, proving the Tipulce could not penetrate the 

 clay. 



j^_ p * * * * * 



18. Chelifer Cancroides. — The habits of that little oddity, 

 the Chelifer Cancroides, seem to have puzzled entomologists ; 

 at least, I cannot discover that they can assign any reason for 

 its attachment to flies' legs. Perhaps the following facts may 

 suggest a few queries which might elicit some light on this 

 curious subject. 



Last summer I watched the manoeuvres oi^ a. Musca Domesiica 

 that had one of these crab-like dependents attached to its femur. 

 It was in the window of a cold and damp out-office. The fly 

 appeared but little annoyed, and continued to travel tardily 

 about the glass, while its hanger-on busily occupied its free 

 claw in seizing such minute objects as came in its way, — at 

 least such appeared to be its business. On attempting to 

 catch the fly, off" it flew to another window with its wingless 

 passenger. I followed closely and quickly, when lo ! the little 

 appendix relaxed its grasp, and dropped itself into a crevice 

 in the frame, where I secured it. Intending to experiment, I 

 put it into a pill-box with a fly, to the leg of which it soon 

 clung, and would, with its neighbour's help, have speedily 

 escaped, had it not been prevented by shutting them up 

 together till another opportunity. But next morning my 

 curiosity was dead. On recollecting these facts, the following 

 queries occur to my mind : 



Does not the Chelifer experience inconvenience, in con- 

 sequence of its construction, when it would be pursuing its 

 prey ? and does it not take advantage of the leg which the 

 fly so readily offers that it may ride out on its hunting excur- 

 sions, and, by the aid of the fly's legs and wings, get cheaply 

 conveyed from place to place ? Is not one of its claws especially 

 adapted for this purpose ? and are not the resorts of the fly 

 those which furnish prey for its occasional companion ? If so, 

 do not these circumstances present an additional instance of 



NO. III. VOL. II. T T 



