MOTIONS OF INSECTS. 311 



aid of wings, this is an astonishing leap. There are 

 several insects, however, which, although they are fur- 

 nished with incrassated posterior thighs, do not jump. 

 Of this description are some beetles belonging to the 

 genus NecydaliS) (Oedemera, Oliv.) in which this seems 

 a peculiarity of the male : and amongst the Hymenoptera, 

 not to mention others, several species of Chalcis, and all 

 that are known of that singular genus Leucospis* 



Many insects, that jump by means of their posterior 

 legs, have not these thighs. This is said to be the 

 case with Scaphidium, a little tribe of beetles a : and one 

 of the same order, that seems to come between Anobium 

 and Ptilinus, found by our friend the Rev. R. Sheppard, 

 and which I have named after him Choragus Sheppardi, 

 is similarly circumstanced. In the various tribes of 

 frog-hoppers (Cercopidtf, &c.) the posterior tibiae ap- 

 pear to be principally concerned in their leaping. 

 These are often very long, and furnished, on their exte- 

 rior margin, with a fringe of stiff hairs, or a series of 

 strong spines, by pressing which against the plane of 

 position they are supposed to be aided in effecting this 

 motion. On this occasion they bend their legs like the 

 grasshoppers, and then unbending kick them out with 

 violence 5 . Many of them, amongst the rest Cercopis 

 spumaria, have the extremity of the above tibiae armed 

 with a coronet of spines ; these are of great use in push- 

 ing them off when the legs are unbended. This insect, 

 when about to leap, places its posterior thighs in a 

 direction perpendicular to the plane of position, keeping 

 them close to the body; it next with great violence 

 pushes them out backwards, so as to stretch the leg in 

 * Trost, Bcitragc, 40. b De Gccr, iii. 161. 



