2 12 THE AMERICAN MIDLAND NATURALIST 



S. D. — Neb. in a great number of instances ought to be read 

 N. D— Neb. (or Man.— Neb.). 



The direct mentioning is indicated by the following figures from 

 the manuals of this century: Britton's Manual (1901) mentions 

 N. D. 13 times, and Dakota (not indicating if N. D. or S. D. is 

 meant) 9 times. Gray's Manual VII (1908), volunteering infor- 

 mation outside of its area, mentions N. D. 20 times, the Dakotas 

 10 times, and Dakota 6 times. A. Nelson's Manual gives N. D. 



3 times, the Dakotas 20 times, and Dakota 1 1 times. Rydberg's 

 Manual (191 7) refers to N. D. 81 times. 



With an overflowing sense of appreciation for the priceless 

 treasures of knowledge we have gathered from all these manuals 

 and their predecessors, we are reminded of the fact, that we now 

 are living in the era of Britton's Manual of 1901 for the east, and 

 Rydberg's Manual of 191 7 for the west. The latter's direct con- 

 tribution of 81 numbers for the western part of this state, covering 

 two sevenths of its entire area, is expected to be followed within a 

 reasonable time by the corresponding number of 200 for the 

 remaining five sevenths, which belong to the area of Britton's 

 Manual, when a new edition of this comes out of press. I am 

 confident that this estimate will be realized. With such prospective 

 direct data of 281 numbers, and the addition of the indirect data 

 and of the "hints", North Dakota will have a splendidly workable 

 botanical map. . 



Leeds, North Dakota. 



