310 W. D. FUNKHOUSER 



base of each maxilla is swollen to form a cylindrical club, which represents 

 in length about one-third of that part of the maxilla inclosed in the head 

 proper. The entire seta is uniformly cylindrical and smooth. It often 

 extends for some length beyond the tip of the labium when extruded. 

 The tip shows some variation, but in most forms it is gradually acuminate 

 to a very sharp extremity. In one species of the genus Thelia (Plate 

 XXXII, 5) the tips of the maxillae show a bifurcate condition, and in the 

 genus Gargara (Plate xxxii, 6) they appear to be curled. It is doubtful, 

 however, whether this is of anatomical significance. 



The mandibles originate likewise from the vertex, but from a point 

 latero-ventrad of the ocelli (Plate xxxii, 3). The base is broadly swollen 

 and bicipital at its junction with the skeleton of the head. Like the 

 maxilla, the mandilile is extended in the form of a long, bristle-like seta; 

 but, unlike the maxilla, this seta is not cylindrical but is flat and lance- 

 like. The extremity is produced into a blade, which is smooth on the 

 outer and sinuate on the inner edge (Plate xxxii, 7). In length the 

 mandibles and the maxillae are al^out equal. 



It will l^e noted that the attachment of the mandibular and the maxillary 

 setae to the vertex does not agree with the conclusions reached in regard 

 to other insects, in which these organs originate from the postgenae. In 

 a large number of dissections of the membracids, however, this structure 

 seemed to remain constant. Whether this condition represents a more 

 or less specialized arrangement, or whether it is the result of migration 

 of organs, can be determined only by investigations beyond the scope of 

 this study. 



The position of the base of the mandibles as described above has been 

 found to vary only in a few of the species of one subfamily — the Mem- 

 bracinae. In this group it apparently arises from the upper part of the 

 clypeus (Plate xxxii, 15). This may represent a still further migration, 

 or a migration in a different direction from the generalized condition. 



THE THORAX 



Superficially the thorax presents the most striking and interesting 

 part of the exoskeleton. This is of course due to the remarkable develop- 

 ment of the pronotum, which is characteristic of the family. The promise 



