128 KANSAS UNIVERSITY SCIENCE BULLETIN. 



These parts are so closely associated with the mouth parts 

 proper (labium excepted), forming as they do a distinct re- 

 gion of the head, which is torn loose in dissection as a single 

 complex of sclerites (32-1), that they will be described in 

 this connection. 



On account of the vertical position of the epicranium, the 

 mouth parts assume an orientation by which the frons, clypeus, 

 and labrum are almost horizontal, their distal ends projecting 

 caudad (28-6). The basal portion of the labium has a similar 

 orientation, but distad of its bend (29-2) it observes a general 

 ventral direction, though possessing some latitude of move- 

 ment cephalad and caudad. 



Frons. — The frons is the largest and heaviest sclerite in this 

 region. Viewed from in front (looking dorsad) it is seen to 

 be obovate in outline (^.9-3). Viewed from the side (fig. 1) 

 its ventral outline is strongly rounded basally, with a dent at 

 about the beginning of the distal third. Its basal edge is 

 thickened (figs. 5 and 1) and continued laterally into proc- 

 esses (figs. 5, 3 and 1) which join the lateral ends of the 

 rod-shaped tentorium, t, and the chitinized rods, cmx. At the 

 place where the rods xijz (fig. 5) above mentioned leave the 

 frons at x, same figure, there springs a ligamentary process 

 (28-h, Ip) , which runs cephalad and dorsad of frons, forming 

 a small plate above the latter, and this plate in turn is con- 

 nected to the vertex by two small ligaments. These are for the 

 attachment of the frons to the head, still leaving some oppor- 

 tunity for motion. The frons is rugose-punctate of surface. 



Clypeus. — The clypeus (29-1, 3, c) is about one-third as 

 long as the frons. It is more or less rectangular as viewed 

 from the front, broader at proximal end, and its lateral edge is 

 bent dorsad, thus partly enveloping the stylets or setse. The 

 slightly curved suture between this sclerite and the frons was 

 clearly marked in most specimens examined, though in a few it 

 was not readily discerned. 



Mandibular and Maxillary Sclerites. — Between the lateral 

 edge of the frons and the rod cmx (29-1), and bounded proxi- 

 mally by the arm of the frons which joins cmx, is a more or 

 less circular foramen through which the bases of the setse may 

 be seen (figs. 3 and 1, for). This foramen is bounded dis- 

 tally by two sclerites; the proximal is crescent-shaped and is 

 known as the mandibular sclerite (fig. 1, mds) ; the distal is 



