Doering: Lkpyronia quaurangulakis. 545 



The vertex (pi. LVI. fig. 1), as has already been mentioned, 

 makes up the largest area of the dorsal part of Ihe head, trans- 

 versely oiH'upying all that part of the head between the eompound 

 eyes and longitudinally all the part between the occiput and tylus. 

 In length and width it is about equal. In the anterior portion of 

 the vertex is the subquadrate invagination into which the front is 

 inserted. The suture between the front and vertex is very distinct 

 and lii'in. hut the parts of the vertex bounding the front laterally 

 do not appeiir to be fastened to the latter, but only to fit down over 

 the line of union of the front and the reflexed corners of the clypeus. 

 The posterior margin of the vertex is broadly emarginate, into which 

 the rounded margin of the prothorax fits snugly, while the lateral 

 margins round to a blunt apex. 



The occiput (pi. LVI, fig. 1) is not visible until after the head has 

 been removed from the body, since it occupies the central portion 

 of the caudal surface of the head, or that part which lies against 

 the cephalic surface of the pronotum. It is a single sclerite, forming 

 the upper boundary of the occipital foramen and the posterior 

 boundary of the vertex. Laterad the lower ends of the occiput fuse 

 with the postgenae, so that the suture appears to stop at a point in 

 a line with the inner margin of the eye. 



The postgence (pi. LVI, fig. 1) occupy the remainder of the caudal 

 surface of the head. They are triangular in shape, with the sharply 

 tapering apex extending between the vertex and occiput. The upper 

 boundary of each postgena is formed partly by the lower margin of 

 the eye and partly by that of the vertex. Its outer margin is the 

 outer limit of the head and its lower end is fused with the occiput. 



The front;, or front (plate LVI, fig. 1), commonly spoken of as 

 the tylus. as will be noted from the foregoing, is located on the 

 dorsal surface of the head. It is subquadrangular in shape, about 

 one-third the width of the vertex and about one-half its length. 



The clypeus (pi. LVI, fig. 2) is located on the ventral surface of 

 the head. Its position has been determined by the fact that the 

 forearms of the tentorium extend to its laterocephalic angles. 



The clypeus is enormously enlarged and protruding, subquad- 

 rangular in shape, widest in the middle and narrower toward each 

 end. In size it extends practically two-thirds the length of the head 

 and over one-half its width. On each lateral margin is a row of 

 parallel grooves separated from each other by a plain, wide, chitin- 

 ous band. These are lighter than the surrounding parts and there- 

 fore stand out clearly. The peculiar reflexed condition of the 



