546 The University Science Bulletin. 



anterior corners and their connection to the front have already been 

 described under the discussion of the tentorium. 



The labruni (pi. LVI, fig. 2) is a flask-shaped sclerite with its 

 broad end attached to the clypeus and its apex truncated. In 

 length it is half the size of the clypeus and in width equal to the 

 width of the clypeus in the neighborhood of the clypeal suture, but 

 narrows down to half the width at its distal end. The suture be- 

 tween the clypeus and the labrum is indistinct along the median 

 line, but is plainly indicated at the sides. The labrum is heavily 

 chitinized and appears to be quite rigid. 



Attached to the caudal end of the labrum and lying on top of the 

 base of the stylets is a small triangular sclerite. This is the epi- 

 pharynx (pi. LVI, fig. 2). It is very thin and lightly chitinized, for 

 which reason it is not readily seen. 



The gence (pi. LVI, fig. 2 1 occupy most of the lateral parts on 

 the ventral aspect of the head. They are irregular in shape with 

 their lateral margins following the contour of the compound eyes 

 and their median margin touching the clypeus and the maxillary 

 sclerite. Caudad they form the outer margin or boundary of the 

 head, which also is the suture between the gena? and postgena?. 



The occipital foramen (pi. LVI, fig. 1) is the opening visible 

 from the caudal aspect of the head. It is bounded dorsad by the 

 occiput and laterally by the postgenai and mandibular sclerites. 



The rostrum (pi. LVI, figs. 1 and 2), or beak, is composed of the 

 labium and two pair of stylets, which are modified maxillae and 

 mandibles. The labium is composed of three segments. The basal 

 segment is the shortest of the three and cylindrical in shape. The 

 second segment is the longest, being about three times the length 

 of the first and twice the length of the distal segment. The last 

 segment is rounded at the tip, its margins seemingly more com- 

 pletely folding around the stylets. The beak is straight and ex- 

 tends backward between the middle coxa? for half their length. The 

 labium is connected by a membrane to both the head and sternum 

 of the prothorax, its point of attachment being just above the tip 

 of the labium. The attachment to the head seems to be the weaker 

 of the two, for when the prothorax is detached from the head the 

 labium usually comes off with it. There is a groove along the ven- 

 tral surface of the labium, in which repose the maxillae and man- 

 dibles. 



The mandibles and maxillm, as in other Homoptera, are setiform 

 or bristlelike. The mandible is connected to the head by a slender, 



