206 NORTH AMERICAN SCELIPHRON (hYMENOPTERA) 



under the compound eyes to form part of the articulation of the 

 mandibles. On each side of the clypeus is a narrow downward 

 extension of the frons bounded externally by the inner margin of 

 the eye, internally by the lateral clypeal suture, and ending below 

 in the lower of two foveae. A second or upper fovea is also 

 present about half way to the top of the clypeus from this point, 

 close to the suture between clypeus and frons, but apparently in 

 the latter plate. The lower margin of the clypeus is normally 

 tridentate, but the relative size and shape of the teeth varies in 

 species and individuals, as will be noted under the descriptions of 

 species. The upper margin of the clypeus is marked by a trans- 

 verse to quite emarginate suture below the base of the antennae, 

 and the lateral clypeal sutures may be continued upward as faint 

 lines, meeting between the antennal pits, thus forming a small 

 triangular area above the truncated apex of the clypeus, or these 

 lines may end at the suture, which is then distinctly emarginate 

 and its ends curve upwards on each side almost to the bases of 

 the antennae. The central area of the clypeus is convex, with a 

 more or less distinct median ridge, and is covered with rather 

 long erect black hairs and closely .set coarse punctures, and may 

 be partially clothed with a silvery pubescence. 



Frons. — The frons lies between the clypeus and the ocelli, but 

 extends downwards on each side between the clypeus and the 

 compound eyes and upwards on each side of the ocellar area as 

 far as the ocello-ocular line. This is a line from the top of the 

 compound eye to the lateral ocellus on each side. The sides of 

 the frons extending along the inner margin of the compound 

 eyes are somewhat sunken below the rest of the facial area and 

 are closely punctate. The frons as a whole is usually covered 

 with coarse erect black hairs, and the sides are more or less 

 clothed with fine silvery pubescence which is seen to the l^est 

 advantage from behind. A short median raised line runs from 

 between the antennae to within a short distance of the median 

 ocellus. 



Ocelli. — The three ocelli lie near the top of the head, forming a 

 triangle with the median ocellus, the largest of the three, below. 

 The base of the triangle, or postocellar line, is always greater 

 than the distance between the median and either lateral ocellus, 



