126 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Clypeus. This sclerite occupies the lower portion of the 

 face below the insertion of the antennae. Its area is indicated 

 by c in the figure. Its free (distal) end is prolonged into a 

 lobe, from beneath which depends the labrum (I). The bound- 

 ary between the clypeus and the frons, the next sclerite above, 

 is indicated by a suture, which, extending obliquely upwards 

 from near the base of the compound eyes, proceeds first to the 

 outer side of the antennal sockets, then obliquely downwards 

 to just below the latter, and finally transversely before them. 

 The angle thus formed by these oblique sutures is marked by 

 a small pit, the base of the hollow ingrowth of each meso- 

 cephalic pillar or arm of the tentorium, which constitutes the 

 endoskeleton of the head. 



Frons. The frons, or front, (/) as we have just seen, is 

 bounded definitely below by a suture, but its upper limits are 

 quite disputable, for here it can hardly be said to do more 

 than to give way to the vertex, since the suture between these 

 two areas is obsolete or nearly so. The frons is of course 

 bounded laterally by the compound eyes ; it bears the antennae, 

 and perhaps the anterior ocellus, at least. The sockets into 

 which the antennae fit are quite proximate; there is a short 

 raised area immediately above them, while laterad of this 

 elevation are the two rather large, smooth antennal fossae or 

 depressions. There is an interrupted line extending from the 

 upper portion of the head to near the antennal sockets. This 

 is the median line of the head. 



Vertex. The vertex is defined in Smith's Glossary of Terms 

 Used in Entomology as "the top of the head between the eyes, 

 front and occiput; in bees that part adjacent to and occupied 

 by the ocelli." If, at least in the more specialized families of 

 Hymenoptera, as the one under consideration, the vertex is to 

 be regarded solely as an area of position, it would occupy the 

 top of the head, as the name would imply, and this, at least in 

 most Larridse, would place the lower boundary of the vertex 

 about at the top of the paired (posterior) ocelli. Regarding 

 the vertex as a sclerite, we would find in certain Hymenoptera 

 that the median impressed line of the frons often forks at or 

 just before the anterior ocellus, but these branches do not 

 extend laterally to the compound eyes, and thus would not shut 

 off the upwards-extending frons (?) from the vertex. Ac- 

 cording to Comstock and Kochi (Am. Nat., XXXVI, 28; 



