264 KANSAS UNIVERSITY SCIENCE BULLETIN. 



in size until at the tip they become stiff bristles. The distal 

 segment is most strongly chitinized and the tip is blunt rather 

 than acute. As in other forms, the lower side of the beak is 

 marked along its median longitudinal line by a seam which is 

 usually taken as evidence of a fusion of two maxillae to form 

 the one organ. 



The Labrum. (Fig. 1.) In the Cicada the labrum is rudi- 

 mentary. It may be seen as a minute triangular process, the 

 apex projecting from the front margin of the clypeus into the 

 opening made by the edges of the labial canal in the first 

 segment. On dissection it is found to be about 3 mm. in 

 length, with its under surface grooved and closely fitted to 

 the underlying epipharnyx. With the change in the manner of 

 securing food, the labrum of course became functionless. The 

 only duty it could perform was to hold the stylets in place, but 

 for this the epipharnyx has become much better fitted. The 

 result has been as one would expect : the labrum is greatly re- 

 duced and the epipharynx has become comparatively much 

 more important. 



The Epipharynx. (Fig. 7, cp.) This organ has necessarily 

 been described in discussing the labrum. In the Cicada the 

 epipharynx resembles the labrum and has usually been con- 

 founded with the latter by investigators. It originates from 

 the lower inner lining of the clypeus, is canal-shaped, cross 

 sections giving a crescent (fig. 9, ep) and projects farther for- 

 ward than the labrum. It will be referred to more explicitly 

 when the stylets are discussed. 



Caudal Views op the Head. (Figs. 3, 4, and 5.) Before 

 proceeding farther in the study of any one organ of the mouth, 

 it will be well carefully to examine the head from the caudal 

 aspect. By removing the head from the body and then the 

 labium from the head, figure 3 may be obtained. On the vertex 

 two large muscles (fig. 3, ml), which fasten at one end just 

 within the occipital foramen and at the other to the prothorax, 

 are prominent. Below them is the head cavity filled with glands 

 which cannot be studied here. Extending from one side to the 

 other across the middle portion of the head is a thin chitinous 

 band, the tentorium (fig. 3, • The median portion is slightly 

 thickened, and this is the tentorium proper. The teudonous 

 strands connecting the median portion with the head wall are 



