Sept., I9i6.] ACKERMAN : CaRPENTER-BeES OF U. S. 207 



cell is formed by the discoidal vein, while its outer margin is formed 

 by the first recurrent nervure. 



At the base of the wing just behind the median cell is the sub- 

 median cell whose hinder margin is the anal vein and whose outer 

 margin is the transverso-medial vein. Beyond this cell and just 

 behind the first discoidal is the second discoidal cell, the outer mar- 

 gin of which is the second recurrent nervure, and the hinder margin 

 the subdiscoidal vein. The large, elongated lower basal cell is the 

 anal cell. Behind the open fourth submarginal cell are two large 

 open cells partially separated by veins and known as the first and 

 second apical cells. On the hinder margin of the fore wing at the 

 end of the anal cell is a broad notch known as the sinus. 



Hind Wings. — In the hind wings there are only three closed cells ; 

 all are basal in position and elongate in form. The anterior one, 

 called the costal cell, is very narrow. It is bordered in front by the 

 costa and behind by the subcosta. The median cell is bordered in 

 front by the subcostal vein, the stigma and the radial ; behind by the 

 media, part of the discoidal and the cubital; and distally by the first 

 transverso-cubital vein. It is the largest cell, being very elongate 

 and tapering at both ends. 



The submedian cell is bordered distally by the transverso-medial 

 vein and behind by the anal vein. The radial cell is open and is sepa- 

 rated from the median cell by the radius. The first submarginal, the 

 first and second discoidal, and the anal cells are all open. On the 

 anterior margin of the hind wing, just beyond the stigma, is a row 

 of frenal hooks or spinuke which hook into the frenal fold in the 

 posterior region of the fore wing, thus holding the two together. A 

 slight sinus is present on the hind margin. 



Legs. — The legs are long and moderately stout, the posterior pair 

 being slightly longer than the others. The tibiae are the only seg- 

 ments of the legs which bear spines; these are located on the distal 

 portion of the inner surfaces. There is one spine present on each 

 tibia of the male, while in the female there is one on each fore and 

 middle and two on each hind tibia. The spines on the fore tibire 

 which fit into a semi-circular indentation on the first segment of 

 each fore tarsus form the antennal comb or cleaner. On the outer 

 surface about half way doM'n on the posterior tibia of the female is 

 an excrescence which is called the tibial scale in this paper. It is a 



