Sept., i9i6.] ACKERMAN : CaRPENTER-BeES OF U. S. 201 



the insertions and the margin of the eyes, in the females; in males, 

 however, the distance between the insertions is greater than that to 

 the eyes. The bulb is quite different in appearance from the re- 

 mainder of the scape. The scape or first antennal segment is by 

 far the longest segment of the antenna and is slightly widened at 

 both ends. The next joint to the scape is the pedicel, which is the 

 shortest segment of the antenna. The flagellum or whip of the 

 antenna is made up of ten segments in the female and eleven in the 

 male. The first joint of the flagellum is always the longest and is 

 narrowed toward its base. The form of the antenna is cylindrical 

 and it is often finely pubescent. 



The mandibles of the female are large and powerful ; they are 

 widest at the base and gradually narrow toward the qpex. In some 

 specimens there is a distinct emargination on the upper side ; also 

 there is some variation in the number of teeth. In all females they 

 are bidentate at the apex but some have one and some two additional 

 blunt teeth on the upper margin. The mandibles are more uniform 

 in the male, always being two-toothed at the apex and without teeth 

 on the upper margin. The front tooth is the smaller and not as 

 pointed as the hind one. The mandibles of the male are smaller and 

 considerably less powerful than those of the female. In both sexes 

 the mandibles bear but few punctures ; there is often a depressed area 

 at the base. They are marked by a prominent longitudinal groove 

 extending along the upper margin and a faint one along the lower 

 margin with a ridge between them. 



The compound eyes are large and oval in form with well rounded 

 ends and protrude considerably from the head. In the males they 

 are as a rule larger than in the females and often occupy two-thirds 

 of the frontal area. They are also approximated on the summit of 

 the head, so that the distance between them is less above than below. 

 The color of the eyes is lighter than the general color of the body, 

 except in fulvous males where it is darker. 



The ocelli, three in number, form a triangle on the vertex. In 

 some species the hind ocelli are a very short distance behind the 

 median one. The posterior ocelli in many species are carinated in 

 front, thus causing them to appear sunken behind; this condition 

 occurs more often in the females than in the opposite sex. There is 

 also a pit or indentation behind each of the posterior ocelli in many 



