STRANGE MODES OF PROGRESS. 353 



Who would expect to find anywhere, save in the thinly- 

 peopled world of monsters, a creature with legs upon its back ? 

 Yet have two such been discovered in the world of insects : 

 one, the bat-louse, 1 which is described as being able to trans- 

 port itself with marvellous celerity from one end to the other 

 of the furry forest wherein it dwells; the other, the grub of 

 a little gall-fly, 2 which inhabits one of the berry-shaped galls 

 common upon oak-leaves. The latter can have, of course, but 

 little room for exercise ; but Reaumur, its discoverer, can hardly 

 be mistaken in supposing that the singular position of its legs, 

 in the centre of the back, is that of all others best adapted to its 

 hollow sphere of action. 



Some insects, again, are not only remarkable for the number 

 of their legs, but also for the remarkable way in which they 

 use them. 



" When centipedes walk backwards, they only use their four 

 hind legs, and these, when they walk in the usual way, are not 

 employed, but dragged after them, like the locked wheel of a 

 coach in driving down a hill. It was first observed, we believe, 

 by Kirby, that a millipede, common under stones, the bark of 

 trees, and the hollow stems of decaying plants, and provincially 

 termed " Maggy Manyfeet," performs its serpent-like motion 

 by extending alternate portions of its numerous legs beyond 

 the line of the body, while those in the intervals preserve a 

 vertical direction." 3 



The fly's walk against gravity, that phenomenon by common 

 observers so little noted, by careful ones so contradictorily 

 explained, and imitated only by some others of the insect race, 

 is sufficient of itself to confer upon that race a remarkable 

 superiority over all others as walking animals. 



Where, above all, shall we find walkers upon water ? No- 

 where, save in the ponds and pools and ditches and rivulets, 

 whereon, almost daily, from spring to autumn, we may see 



1 Nycteribia Hurmanni. 2 Cynips Quercus inferno. 



3 " Insect Transformations." 



