257 



SPECIALISATION OF LEAPING LEGS 



OF LOCUST. 



HENRY CROWTHER, F.R.M.S., 

 Curat 07- of the Philosophical and Literary Society s Museum, Leeds, 



ALdipoda 



being imported to this country in vegetables from the south of 

 Europe, was left with me for a short time by Miss Parkinson, 

 of Harrogate, who had secured it in a Leeds greengrocer's shop. 

 It lived for about two weeks, and though I offered it many kinds of 

 food I was unsuccessful in tempting it to eat. Up the sides of the 

 large glass bottle in which it was kept, it had no difficulty in 

 climbing. Locusts are saltatorial insects, their hinder legs being 

 strongly developed to subserve this purpose, but a special modifica- 

 tion, of which I have seen no record, to ensure the full purchase of 

 the legs when leaping, may be of interest. The observations which 

 follow are from the Leeds specimen. 



rn 





The femur or thigh of the hinder leg is very large and tapers 

 somewhat suddenly towards the distal end, and then enlarges into 

 a knob. Within the upper portion of the knob the tibia or shank is 

 jointed, whilst the outer part of the enlargement acts as a guide and 

 stay to the shank. If the tibia be folded on the femur it will be 

 found that the superior edge of the former fits into a ventral groove 

 of the latter. In this closed or locked position the tibia has no 

 lateral movement. 



I pass over, as it does not concern us here, a description of 



the arrangement of the strengthening bars of the femur, which 



remind one of the flanges and diagonals of a Warren girder. 



All the femora and tibiae of the insect are adorned with a few 

 straggling, long, simple, white hairs of no special interest. 



The tibia is somewhat straight, of about one-quarter the thick- 

 ness of the femur, its superior aspect, when locked, or anterior 



when the insect is walking, is rounded to fit the inferior groove of 

 the femur, and carries at its distal end two pairs of tibia! spines 

 which are long and strongly recurved. On its inferior, or posterior, 

 aspect are about twenty-four slightly inclined, sharply pointed, 

 chitinous spines, tipped with black. They are so arranged in 

 a double row as to form a spined groove, with fourteen spines; 

 counting two of the four superior distal spines, which are produced 

 and curved sufficiently to fall in line with the inferior tibial spines, 

 on the inner side of the tibia, that nearest the body of the insect, 



Sept. 1896. * 



