18 



this shows but one, and the entire tarsug but three joints. The tliird or 

 terminal joint is furnished at the tip with two claws (ungues), between which 

 in all the groups except Tettigini there is a circular piece or pad {pulviUus, 

 ¥ig.2,pl). 



The posterior legs are much longer and stouter than the anterior or 

 middle pair, in order to fit these insects for leaping. The thighs or femora 

 are swollen or incrassated near the base* to accommodate the muscles neces- 

 sary for this purpose. The external face, which is sometimes called ihedisk, 

 is marked by numerous alternate minute ridges and furrows running obliquely 

 inward and forward from each margin toward a longitudinal middle furrow, 

 giving the entire disk a pinnate appearance; hence these minute ridges are 

 sometimes alluded to as the innncB of the femur. The disk is bounded above 

 and below by a small but usually distinct carina. Along the middle of the 

 upper edge runs another keel, to which the name up2)er or superior carina is \ 



frequently applied. This is sometimes simply a raised line or angle; but in 

 other cases, especially in some genera of the group CEdipodini, it is quite promi- 

 nent. The inferior edge is generally channeled for the reception of the tibia 

 when folded up. The outer margin of this channel or sulcus is the loicer or 

 inferior carina, and generally corresponds in prominence with the upper one. 

 The femur affords some useful characters in describing species, by its length 

 as compared with that of the abdomen; by its size, whether comparatively 

 slender (PL, Fig. 1) or broad (PL, Fig. 5), by the greater or less prominence 

 of its carinse, &c. 



The method by which the tibia is articulated with the femur admirably 

 adapts it for leaping. The apex of the femur is suddenly exjjanded vertically, 

 but deeply channeled, leaving a plate on each side, between which the base 

 of the tibia is inserted. This has here two short right-angular bends, the 

 articulation being at the sides of the first angle with the lateral plates of the 

 femur; thus leaving a short lever extending upward, to which the strong 

 extensor muscle is attached. The flexor muscle is attached beneath in the 



* The base is the end by which a part is joined to the body directly or indirectly ; 

 thus the base of the abdomen is the part by which it is joined to the thorax. The base 

 of the autenufE is the iiart by which they are connected with _the head ; the base of 

 the elytra or wings, the part by which they are joined to the thorax; and the base of 

 the tibite is the part which joins the femur and not the end that rests on the ground. 

 Tip or apex always signifies the part or end oi)po.site the base. The only doubtful use 

 of these terms is that with respect to the prouotum, the tip in this case being the pos- 

 terior extremity. 



