Doerixg: Lepyronia quadrangularis. 543 



margin of the rcflexed corner has become strongly fused to the 

 lateral margins of the tylus. It is not strange that with the peculiar 

 arrangement of these sclerites, as well as the compression of the 

 head on the anterior portion, that the tentorium has assumed a 

 peculiar position also. In the first place, the anterior portion of the 

 forearm of the tentorium has become forked. The prongs are 

 blunt at the end and are of unequal length. The sm,aller one is at- 

 tached to the skeleton of the head at a point about midway on the 

 clypeus (fig. 3) and just back of the antennal pit. If the tentorium 

 stopped here it would indeed be hard to identify the clypeus, since 

 it is equally as far from either of the anterior margins of the two 

 sclerites in question. Even in that case it would seem more plausible 

 that it should have migrated backward due' to the flattening of the 

 head, already described, than that it should have migrated so far 

 forward for no accountable reason. Fortunately, however, the other 

 branch of the fork extends farther cephalad. It curves slightly 

 mesad, following the free margin of the reflexed clypeus, although 

 not touching it. In fact, it extends as far forward as the corners of 

 the clypeus at the point where the latter is attached to the latero- 

 posterior angle of the tylus. The tip of the branch appears to be 

 attached by a membrane to the ental surface of the vertex. The 

 significance of the position of the tentorium at this place in the 

 attempt to, locate, the front and clypeus seems to be this: If the 

 reflexed corners of the clypeus were bent back in their normal 

 position and the front and vertex were laid out on the plane of the 

 rest of the head sclerites, then the anterior arm of the tentorium 

 would extend to the laterocephalic margin of the sclerite labeled 

 clypeus in figure 3. The sclerites of the head from this view could 

 easily be designated in succession as the vertex, front, clypeus, 

 labrum and epipharynx without any intervening unexplained tylus. 

 Another argmiient for such nomenclature is the position of the 

 median ocellus and its relation to the frons. Referring again to 

 Comstock and Kochi (1902), we find a statement to the effect that 

 the frons, in the more generalized insects at least, bears the median 

 ocellus. Funkhouser (1917) is of the opinion that in the Mem- 

 bracidae the frons has disappeared and with it the median ocellus 

 which it contained. While Crawford (1914), in his work with 

 Psyllidae, states that in all cases where the frons is present it bears 

 the anterior ocellus at its base or at the end nearest the vertex. 

 In the Cicadidae the median ocellus is distinctly located on the 

 dorsal surface of the head in the sclerite just above that which is 



