542 The University Science Bulletin. 



the sclerite. Without a doubt the clypeus of which they speak is 

 the frons of other writers. 



According to these writers, then, a different nomenclature from 

 the commonly accepted one for the sclerites of the head of the 

 Cicada has been used. The same thing holds true for Lepyronia 

 quadrangularis. The sclerites on the ventral surface of head would 

 be labeled clypeus, labrum and epipharynx (pi. LVI, fig. 2). In 

 figure 1, the vertex remains the same, but the tylus would be termed 

 the front. 



A study of the tentorium and the position of the ocelli bear out 

 this homology for both the Cicada and Lepyronia. As was men- 

 tioned above, Comstock and Kochi (1902) showed that the ends 

 of the suture between the front and clypeus extend to the invagina- 

 tion which forms the anterior arms of the tentorium. From this 

 it follows necessarily that the position of the tentorium would un- 

 doubtedly prove the identity of -the front and clypeus in these in- 

 sects. The tentorium (pi. LVI, fig. 3) is of practically the same 

 shape in the Cicada and in Lepyronia. It consists of a slender 

 transverse bar, which is the basal part or body of the tentorium, 

 from which two long, slender, chitinous arms extend cephalad, and 

 two short, posterior arms extend laterad. In the Cicada the basal 

 portion is fairly narrow, not extending over one-third of the width 

 of the occipital foramen; it occupies a central position in the head 

 cavity. The anterior arms are by far the longest part of the 

 tentorium and can easily be seen to run almost directly cephalad 

 and slightly laterad to the point' which marks the cephalolateral 

 angle of the large protruding sclerite or clypeus. The tentorium 

 in Lepyronia quadrangularis varies somewhat from that of the 

 Cicada, but is essentially the same. In the cercopid the basal part 

 of the tentorium is more extensive, in that it occupies about two- 

 thirds of the width of the occipital foramen. The anterior arms 

 extend in much the same direction as the Cicada, but their extreme 

 anterior portions have become somewhat modified, due, no doubt, 

 to the peculiar compression of the head. At this point it would 

 probably be clearer to follow the figure (pi. LVI, fig. 3). In this 

 figure the head is in the exact position as in figure 1, with the ex- 

 ception that the vertex has been removed in order to show the 

 tentorium. The vertex appears to be very loosely attached to the 

 tylus, for it can readily be lifted away. After the vertex has been 

 removed the connection of the tylus and clypeus can easily be seen. 

 The anterolateral corners of the clypeus are reflexed and the cephalic 



