FAM. MEMBRACID^ aS 



body of the segtnent but in the coxal cavity. This separate piece is beheved to be a subdivision of 

 the coxa and originally a part of that sclerite. 



The trochanter is normally an elbow-shaped segment attached to the ventro-mesal extremity of 

 the coxa. The proximal half projects directly ventrad, while the distal half turns ventro-mesad. The 

 segment is freely movable in the Membracida, and the articulation with the coxa is comparatively weak. 

 The coxa-trochanter joint, however, is often strengthened by overlapping hooks or projections. 

 No special modifications are found in the trochanters of the first or the second pairs of legs, but in 

 those of the hind legs most interesting developments may be found. The commonest variation is that 

 of general shape. In most species the segment is practically cyUndrical, bent in the middle but nearly 

 equal in diameter at each end. This shape graduates to a roughly spatulate outhne in which the proxi- 

 mal end is much narrowed and nearly cyhndrical while the distal end is broadly flattened and paddle- 

 hke. In certain species of the subf. Membracina the segment is shortened and nearly straight, the 

 internal angle being hardly recognizable and the articulatory surfaces almost in a line with each other, 

 giving the entire segment a spindle-shaped outline. By far the most interesting modification of the 

 trochanter, however, and one that is extremely valuable for systematic purposes, is the development of 

 teeth on the internal surface of the distal half. When teeth are present the distal end is expanded into 

 a flat plate, or disk and the disk is often hoUowed out in the center. The commoner type, however, 

 is the arrangement of the teeth over the entire surface of the disk with those on the margin shghtly 

 larger than the others. The disk is often elevated to a considerable distance above the body of the 

 trochanter, and its surface between the spines is usually pebbled or thrown up into slight nodules. 

 From a strictly lateral view the edge of the trochanter appears merely dentate, and the opposite edges 

 of the same disk are not uniform in number or position of the teeth. In some species the teeth are 

 very small and cone-shaped and in almost all cases they are jet-black in color. An interesting feature 

 in connection with the presence of the teeth is the shifting of the attachment of the femur. Ordinarily 

 the femur is attached to the lateral end of the trochanter nnd extends more or less laterally from the 

 body. When the teeth are present, the plate, or disk, that bears them is developed from the region 

 at which the femur ordinarily articulates. This forces the base of the femur around to the mesal 

 rather than the lateral angle, and the femur is thus forced to point farther inward or else develop a 

 cuive in its proximal end. The faces of the toothed disks of the two trochanters oppose each other 

 when the legs are in the normal position, and if the legs are brought close together the teeth meet and 

 interlock. No explanation has ever been offered as to the function of these teeth, and their utihty 

 is questionable. Another character that is apparently closely related to the toothed condition is found 

 in the hairs, or bristles, which often occur on the internal face of the trochanter in many species. 

 The fact that these bristles are borne on the same area which gives rise to the teeth in the armed forms, 

 and that the genera in which the bristies are found are closely related to those that bear teeth, would 

 suggest that the two forms of modification may be the response to similar orthogenetic tendencies. 



The femora show the least variation of any of the leg segments in the Membracide. In shape the 

 femur is usually club-like and often much curved. The proximal end is swollen, and the segment grad- 

 ually narrows toward the distal end. The distal end is in some cases suddenly expanded to form a 

 knob, or head, and before this is a slight constriction, or neck. The entire segment is subcyhndrical, 

 seldom flattened, and never angular. It is the largest and strongest segnient of the leg and doubtless 

 furnishes the chief power in jumping. The distal end is hoUowed out to receive the end of the tibia, 

 and usually projects slightly on either side into a plate to direct and strengthen the knee-joint. The 

 femur is much inchned to pubescence, but in this respect it follows the general tendency of the leg as 

 a whole and does not differ froin the other segments. It seldom possesses a color pattern, even in 

 gaudily decorated species. 



