4 Myron Harmon Swcnk 



of the writer, and at present deposited with the University of 

 Nebraska. 



CLASSIFICATION" 



The classification to be employed in this series of papers does 

 not agree in all respects with any in current use by apidologists. 

 It is, however, very largely based upon the excellent classification 

 proposed by Robertson {Canadian Entomologist, XXXVI, pp. 

 37-43, 1904), modified along several lines proposed by Cockerel! 

 (University of Colorado Studies, \ll, pp. 181-88, 1910). In 

 the present paper, as well as in those to follow, the classification 

 of the subfamilies, genera and subgenera as they appear to the 

 writer will be given in connection Avith each family, so far as the 

 Nebraska species are concerned, and after the completion of the 

 series a synopsis of the families will be given. The families will 

 be taken up individually, not in any phyletic sequence but in the 

 sequence best accommodated to the immediate circumstances of 

 preparation and publication. 



MATERIAL 



The present paper is the result of a careful study of over eight 

 hundred specimens of the genus Nomada, w^hich is the only valid 

 genus of the family Nomadidae, except J^icreckella, found within 

 our limits. Of these, all but about one hundred specimens were 

 collected within the state of Nebraska, and many of the species 

 are represented by large series which gives considerable oppor- 

 tunity for the study of variations within the species. As a result 

 of this the nomenclatorial standing of a number of forms is 

 changed at this time, while a few nominal species and subspecies 

 are shown to be synonyms. Fifty-three species and subspecies are 

 represented in the Nebraska collections, which gives the state 

 about one-sixth of the North American fomis. Of these, nine- 

 teen species and three subspecies are apparently new and are 

 here described and named, while from outside the state ten 

 species and two subspecies are described as new, making a total 

 of thirty-four new forms presented in this paper. In addition to 

 this material the writer recently availed himself of the oppor- 



