52 \VM. H. ASHMEAD. 



respect with many genera in this family, Halictus and allies, except 

 that the pollen brush or flocculus is wanting on the hind femora, and 

 thin and spars.', or scarcely noticeable on the hind tibise and tarsi. 



It is not quite exact to say that the flocculus is wanting on hind 

 legs in the Sphecodime, for it is really present, although much re- 

 duced, but yet sufficiently developed to retain pollen. 



His family Melittidse, containing only two genera, is also sup- 

 pressed : Gilissa being placed with the Andrenidse, Macropis with 

 the Panurgidse. 



I also consider his family Melectidse — my family Nomadidse, in 

 part (= subfamily Nbmadinse Friese) — a composite one; many of 

 the genera he has placed in it, such as Pasites, Melittoxena, Ammo- 

 bates, etc., not belonging to it, but, according to my views, should 

 be placed with the Stelididse. Their relationship to the Nomadidse, 

 if it ever existed, must be certainly very distant. 



For the genus Ceratina, placed by Schmiedeknecht in his family 

 Xylocopidse, I have erected the family Ceratinidse, since it seems to 

 me to present scarcely any character in common. 



The genus Colletes, Schmiedeknecht placed with the Andrenidse. 

 The Andrenidse, as now restricted, will not permit this arrangement, 

 since the mouth parts in Colletes are too entirely different from those 

 of the genuine Andrenidse. it is clearly related to the Prosopidse, 

 where Bingham (Fauna India Hymenopteraj and Friese have 

 placed it. 



It differs, however, in several particulars from Prosopis and allies. 

 For instance, the front wings have three cubital cells, the head and 

 thorax are densely pubescent, while the hind legs in the 9 have a 

 dense scopa, characters of great taxonomic importance (not possessed 

 by Prosopis), and which seem to me to forbid its retention with the 

 Prosopidse. 



There are several genera closely related to Colletes, having all the 

 above characters in common, and for these I have retained the 

 family name Colletidse, first proposed by Col. Bingham. 



In the arrangement of the families and genera in this work, I 

 have attempted to bring together or in juxtaposition, such as have 

 had seemingly a common origin or ancestry, or exhibit strong affini- 

 ties. For I believe with Dr. Friese and others, that the commensals 

 and parasitic bees are nothing more than offshoots from other bees, 

 just as I believe and have already published, that the Ichneumonids 

 are offshoots from plant-feeding wasps, Siricidse, etc. ; that the inqui- 



