1914 ENTOMOLOG-ICAL SOCIETY. (ir, 



in no part of its course is it as distinct as in Pamphilius, while the occiput can 

 be identified as a narrow band of cuticle closely fused with the vertex and gense. 

 There is no well marked suture between the occiput and jjostgenas in Cimbex. 



On the ventral pai-t of the cephalic aspect, there is a distinct suture in both 

 Pamphilius and Cimbex and related species connecting the ventral ends of the 

 arms of the epicranial suture. This is the clypeal suture (Figs. 2, 3, and d, c), so 

 named from the fact that it separates the two parts of the clypeus and should not 

 be confused with the fronto-clypeal suture (Fig 2, fc), which will be described 

 later. 



Adjacent to the ventral margin of the front and the ventral ends of the arms 

 of the epicranial suture there are several small sclerites. Just ventrad of the 

 middle of each arm of the epicranial suture, there is a distinct pit, which marks the 

 point of attachment of the dorsal arms of the tentorium (Figs. 2 and 3, td). At 

 the ventral ends of the arms of the epicranial suture, there are also distinct thick- 

 enings, which mark the point of attachment on the ental surface of the head of the 

 anterior arms of the tentorium. There are short sutures extending from the point 

 of attachment of the dorsal arms of the tentorium to the clypeal suture. The 

 small triangular areas (Figs, 2 and 3, ap) on each side enclosed by the sutures Just 

 named and the arms of the epicranial suture have been given the name of antecoxal 

 pieces of the mandibles by Comstock. They do not so far as I am aware occur 

 other than in the larvae of insects with a complete metamorphosis and then only in 

 the more generalized groups. In the ventral margin of each antecoxal piece, there 

 is a distinct notch. This notch forms an acetabulum for the cephalo-mesal condyle 

 of the mandible. 



Along the ventral margin of the gena there is another small, transverse seler- 

 ite, which is also peculiar to generalized insects, but is found in both larvse and 

 adults. The mesal end of this sclerite (Figs. 2 and 3, tr) is adjacent to the ante- 

 coxal piece of the mandible. These sclerites have been named by Comstock the 

 trochantins of the mandibles. They are well developed in Pamphilius. 



In Pamphilius there is a faint transverse suture (Figs. 2, fc) extending from 

 the middle of the suture forming the mesal boundary of an antecoxal piece to the 

 corresponding suture of the opposite side. On the ventral side of this suture, there 

 is a narrow transverse plate (Figs. 2, 3, and 9, cl), bounded on its ventral side 

 by the clypeal suture. This narrow plate is the first clypeus and the plate along 

 its ventral margin and separated from it by the clypeal suture is the second 

 clypeus (Figs. 2, 3, and 9, c2). The faint suture extending between the antecoxal 

 pieces and forming the dorsal boundary of the first clypeus is the fronto-clypeal 

 suture. The second clypeus usually has its lateral margins oblique and its ven- 

 tral margin emarginate. In many species of larvae the fronto-clypeal suture is 

 obsolete and the first clypeus is fused with the front, but in some the first clypeus 

 has been greatly reduced in size and the clypeal suture becomes faint or obsolete 

 and the fronto-clypeal suture is distinct. In generalized adult insects, the clypeus, 

 so called, is a fusion of the antecoxal pieces of the mandibles, and the first and 

 second clypeus ; the lateral ends of the clypeal suture are frequently distinct and the 

 mandibles are articulated with the lateral ends of the clypeus. This articulation is 

 undoubtedly homologous with the articulation found in the antecoxal piece of the 

 mandible described above. 



There is a small movable flap, the labrum (Figs. 2, 3, and 9, 1), attached to 

 the ventral margin of the second clypeus. The labrum is usually emarginate along 



5 E.S. 



