CLASSIFICATION OF THE BEES. 79 



the Nbmadidae — in the nests of other bees, species belonging to it 

 having been bred from the cells of Anthophora, Megachile, Anthi- 

 dium, Osmia, etc. All are without a ventral scopa, and also with- 

 out scopa on the hind legs. 



The species composing it come nearest to the Megachilidae, and 

 some of the genera, as has been suggested by Dr. Friese, are off- 

 shoots from some of these bees. 



The parasitic habits, so noticeable in various groups of insects, 

 primarily or originally, I think, must have been evolved or devel- 

 oped independently, through lack of sufficient food supply, until it 

 became acquired and hereditary in the offspring, 



The family is dividable into two subfamilies: 



Table of Subfamilies. 



Claws with pul villi between Subfamily I. Stelidin^e. 



Claws without pulvilli between Subfamily II. Ccelioxin^;. 



Subfamily I. Stelldin^e. 



The bees placed in this group, as with the Osmiinse in the Mega- 

 chilidse, always have a distinct pul villus between the claws, which 

 readily separate them from those found in the Ccelioxinse. 



Dr. Henry Friese suggests that the group, or at least the genus 

 Stelis, originated from Anthidium. 



Five genera are now recognizable : 



Table of Genera. 



Second cubital cell receiving only one recurrent nervure, the second recurrent 



uniting with the cubitus behind the transverse cubitus 2. 



Second cubital cell receiving both recurrent nervures. 



Abdomen black or blue-black, usually with white transverse bands or macu- 

 late; mandibles tridentate; maxillary palpi 2-jointed; % with the 

 pygidium subemarginate, the hypopygium tridentate. 



JVIelanostelis Ashm. 

 2. Abdomen black or rufous and black, immaculate, clothed with a scattered pu- 

 bescence; scutellum rounded and produced behind over the base of 



the abdomen 4. 



Abdomen black or rufous, and most frequently ornate with white or yellow 

 spots; scutellum quite differently shaped, normal or with lateral teeth ; 

 maxillary palpi 1 or 2-jointed (rarely wanting) ; labial palpi 4-jointed. 



Scutellum with lateral teeth behind ; head narrower than the thorax 3. 



Scutellum without lateral teeth behind ; head fully as wide as the thorax. 



Clypeus not lengthened, well rounded ; maxillary palpi 1 or 2-jointed ; 



abdomen semiglobose, the segments broadly banded with yellow or 



white, as in Anthidium, £, with the anal segment entire, rounded, 



ending in a strong thorn- • • • l'rotoslelis Friese. 



TRANS. AM. ENT. SOC. XXVI. JUNE. 1899. 



