Studies of North American Bees y 



considerations would again point to Nomada riificornis as the 

 type of the genus. 



The first definite designation of a type in Nomada was by 

 Latreille in 1810 {Considerations generates sur I'ordre naturel des 

 animaux, etc., p. 439), when Nomada fabriciana (Linnaeus) 

 Fabricius was designated as the type; but since we cannot at- 

 tribute the genus to Fabricius because of Scopoli having used the 

 name five years previously, and as Scopoli did not include A^ 

 fabriciana among his species, obviously fabriciana cannot be the 

 type species of Nomada. Curtis in 1832 (British Entomology, 

 IX, no. 419) designated the type of Nomada as N. riificornis and 

 this may be considered as definite type designation for the genus, 

 involving as it does an originally included species. Westwood, 

 moreover, in 1840 (Synopsis of the Genera of British Insects, II, 

 p. 85) also referred to A'', riificornis as the "typical species" 

 under Nomada. 



SUBDIVISIONS OF THE GENUS NOMADA 



The genus Nomada, in a broad sense, is comprised of a large 

 complex of forms, over 270 named species and subspecies from 

 North America alone being included in the recent enumeration 

 by Cockerell (Proceedings U. S. National Museum, XLI, pp. 

 226-36), which have so far defied successful subdivision into 

 valid genera, although the desirability of such a division is obvious 

 and numerous conscientious attempts have been made to do so. 

 The group as a whole seems to intergrade at various points in 

 practically every promising character which has been employed 

 and tested, so that an absolute separation on these characters 

 would place closely allied forms widely apart and bring together 

 forms quite unlike, and, as to constitute a really valid genus the 

 breaks in the evolutionary series should be sufiiciently marked 

 that the groups can be distinctly and trenchantly set ofif, the 

 possibility of successfully subdividing Nomada into good genera 

 seems quite remote. Various fairly well defined though inter- 

 grading groups are recognizable, however, which if the char- 

 acters are not absolutely applied will separate the species into 



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