1902] A REVISION OF THE GENUS NEMO PHIL A 195 



almost infinite variation makes an accurate limitation of species 

 absolutely impossible ; and most of the species as here described 

 include a great variety of more or less inconstant forms. Were 

 these all described they would fill a volume, but nothing would 

 be gained thereby. Convenience should be the aim of classifi- 

 cation, and this aim is most effectually defeated by the multi- 

 plication of uncertain species. 



To avoid possible uncertainty in interpreting the descriptions, 

 it should be said that measurements of leaves are given as 

 including the petiole ; but the outlines as including only the 

 blade, except where there is a conspicuously tapering base. 



The question of the relation of Nemophila to Ellisia is vital, 

 but must be left for future consideration. 



The writer is indebted to the following persons for assistance 

 in the preparation of this paper, principally by the loan of 

 specimens: Mr, and Mrs. T. S. Brandegee, Miss Alice East- 

 wood (for the California Academy of Sciences), Dr. }. N. Rose 

 (for the United States National Museum). Mr. S. B. Parish, 

 Mr. H. M. Hall, Mr. J. P. Tracy, Prof. W. R. Dudley, Mr. Leroy 

 Abrams, Mr. J. G. Lemmon, Prof, Aven Nelson, Prof. C. V. 

 Piper, Mr. W, C. Cusick, Mr. Thomas Howell, Mr. Geo. Han- 

 sen, Mr. M. L. Fernald, Prof. L. F. Henderson, Prof. A. J. Cook, 

 Mrs. Mary H. Manning, Miss Winifred Paine, Mr. R. H. Piatt, 

 Mr. W, N. Suksdorf, and Mr. Ralph Hopping. Special acknowl- 

 edgment is due to the members of the Department of Botany of 

 the University of California, and particularly to Prof. W. L. 

 Jepson, at whose suggestion the study was first undertaken and 

 whose constant encouragfement and advice have been invaluable. 



KEY TO THE SPECIES. 



Flowers I ^"^ or more across (except no. 2). 



Leaves (at least the upper) alternate; seeds less than 5. 



Angles of stems and often veins of leaves beneath retrorsely prickly. 

 Petioles broadly winged and auriculate-clasping; flowers i to 3 



cm 



across 



I. N. aurita 



Petioles not winged nor auriculate-clasping; flowers less than i*" 



m 



across 



2, N. racemosa 



