FAM. MEMBRACIDA-: i5 



The labrum is a single, heavily chitinized, subcylindrical piece attached to the distal end of the 

 clypeus and projecting usually ventro-caudad from that sclerite. Because of the incUned or prone 

 position of the head, this piece is not visible except occasionally at its basal part from a strictly cephalic 

 view of the insect. Little variation is noticed in the labrum, but in the subfamily Platycotina \t tends 

 to be shorter and stouter than in other membracids. AUhough in the Membracida the labrum should 

 perhaps be considered as one of the head segments and not as an appendage, it is more or less movable 

 and probably serves to support and guide the rostrum. 



At the extremity of the labrum arises a small triangular piece, the epipharynx. This sclerite 

 is always distinct in both nymph and adult. In the former it appears as a soft, light-colored fleshy 

 extension of the labrum ; in the latter as a stiff, hard, sharp segment distinctly set off at its base. In 

 posltion it follows the general course of the labrum. 



The genae form the lateral outline of the head and give the facial contour which is sometimes 

 used in systematic diagnosis. Each gena is irregular in shape, being bounded dorsad by the vertex 

 and mesad by the clypeus. Its lower extremity is contiguous with the base of the labrum. In general 

 outHne it is usually a long, rather flat plate, beginning at the lower margin of the eye and continuing 

 to the rostrum. In the Smiliina the ends are more or less pointed and the middle is swollen ; in the 

 Membracina the entire sclerite is inclined to be nearly quadrangular. The genae are not set in the same 

 plane as the frontal surface, but extend slightly caudad, so that the width ot the sclerites determines in 

 part the depth of the head. 



Just behind the genas and forming the basal surface of the epicranium are the postgenae. These 

 sclerites extend from the occiput to the labrum and are most irregular in shape. The upper extremity 

 of each sclerite is projected laterad in a broad disk which almost entirely covers the hinder part of the 

 eye. The inner edge bounds the occipital foramen and the lower end fuses with the lateral margin 

 of the labrum. The extreme ventral projection foUows the line of the labrum on the inner margin and 

 the genae on the outer cephalic, and ends in an attenuated point. 



The occipital foramen, as will be noted from the foregoin;,', is an almost circular opening, its 

 edges lined with a thin connective-tissue membrane which is continuous with a like membrane from the 

 inner body wall of the prothorax. This conjunctival membrane is of greater extent in the nymph than 

 in the adult. 



The rostrum, or beak, consists of a two-jointed labium containing the bristle-like maxilla; and 

 mandibles. It is stout and heavy, and is better developed in the nymph than in the adult. In the 

 former it is rather fleshy and svvollen; in the latter it is harder and more slender. The length of the 

 rostrum has been used as a systematic character ; but this character not only is of very doubtful value, 

 but is hard to determine owing to the fact that the rostrum is carried flat against the ventral surface of 

 the body. It may be hardly longer than the labrum or it may extend caudad beyond the hind coxae. 

 This variation is, to be sure, great, but is not constant. Neither within the genus nor within the 

 species has this character been found useful in systematic work. 



The labium in the Membracida does not differ essentially from that organ in other Homoptera. 

 It consists of two segments, the basal segment being two or three times as long as the distal. The 

 labium is grooved and bears within the groove the mandibular and the maxillary seta;. The entire 

 organ is movable, and when the insect is feeding it projects downward at riglit angles to the body. 

 When not in use it is folded back betvveen tlie coxas on the median ventral line of the body. In every 

 form studied, the labium has been found to be straight, and no cases have been discovered in which 

 the distal segment was bent forward as has been shown to be the case in certain other Hemipteia. 



The maxillae are modified to form long, bristle-like seta;. They originate from the inner surface 

 of the vertex above the ocelli, at a point about midway between the oceUi and the margin of the occiput 



