1 INTRODUCTION. 



The limbs are specially adapted for this mixed 

 motion, being fornished with strong spm^s and rows of 

 fine setae, which take a hold on any roughness which 

 presents itself as a "point d'appui." 



Powerful muscles are required to work the legs, and 

 therefore the femora and coxae are robust. The tibiae 

 are very long, and to these are attached the greater 

 number of spines and hairs. Most markedly this is 

 so on the third pair of legs. In the Cercopidae we 

 find tw^o or more coronets of spurs on the tibiae and 

 tarsi. In the Delphacida), a characteristic tibial serrated 

 plate is seen near the tarsus, which plate is well-fringed 

 with prehensile setae. 



To enable the insects to carry their legs easily, the 

 femora are long enough to project beyond the inser- 

 tions of the elj^tra ; and thus the tibiae fold back, and 

 do not extend much beyond the apex of the abdomen. 

 The femora also are curved and flattened, so as to lie 

 parallel to the tibiae, and this is always the position 

 assumed by the insect before taking a leap. The 

 knees being placed well forward, and then sud- 

 denly extended, the spines become engaged with 

 the pilose coats of the grasses, &c., and the leap is 

 effected. 



If a flea can leap two hundred times its own length, 

 a man, in proportion to his size, could jump higher 

 than any building yet constructed. Many small Tetti- 

 gidae make more surprising leaps, but the larger 

 kinds progress chiefly by short flights. The two front 

 pairs of legs are used also for running backwards, 

 forwards, and sideways. This last action seems to be 

 peculiar to the Tettigidae, and their odd crab-like 

 movements might almost suggest a possible example 

 of atavism to that articulate class. 



The tarsi are composed of three joints, the last of 

 which ends rather abruptly. The claws are minute, 

 curved, and sometimes accompanied by pulvilli. 



The number of tarsal joints has always been con- 

 sidered of great importance in insect classification ; yet, 



