•82 TRANSACTIOKS OF THE [fEB. 23, 



clature, but it is the best and most convenient at present avail- 

 able. It has its objections, which, theoretically, seem insuper- 

 able, but which, in practice, prove insignificant. 



At first, under this method, lumping flourished to a remark- 

 able degree. Forms that were known to intergrade were not 

 only reduced to subspecies, but not infrequently such reduc- 

 tions were made on theoretical grounds. Certain forms. Judg- 

 ing from what had been established as occurring in allied groups, 

 and in accordance with what might be presumed to occur as 

 the result of certain laws of geographical variation, were pre- 

 sumptively merged with others, sometimes correctly, but often 

 improperly. 



It was during this phase of affairs that the " Monographs of 

 North American Kodentia" appeared, as also Coues'^' Fur- 

 Bearing Animals'' and my '' North American Pinnipeds.'' 

 It was also from this point of view that True prepared his 

 "Check-list of North American Mammals," published in 1884. 

 Incidentally both Coues and myself did some revisionary work 

 in other groups, on nearly the same lines. 



To throw into strong contrast the work of the three leading 

 periods in the recent history of North American mammalogy, 

 we will compare briefly two or three groups as left by Baird in 

 1857, by Coues and Allen in 1877, and as they appear from the 

 standpoint of to-day. For this purpose we will select the 

 MuridaB, or the field rats and mice ; the Saccomyidae, or the 

 pouched rats and mice ; the Leporidre, or the hares ; and the 

 .Sciuridfe, or the squirrels, spermophiles, and marmots. 



In 1857 Baird recognized forty-eight species of field rats and 

 •mice; of these Coues reduced eighteen to synonyms and three 

 ■others to subspecies. There has been no recent revision of the 

 group as a whole, nor in fact of any of the genera. An entirely 

 new genus, however, of meadowmice {Phenacomys), with four 

 species, has been recently described by Dr. Merriam/ of which 

 not a single specimen had been recognized by naturalists three 

 years ago, although the genus is now known to range across 

 North America from British Columbia to Labrador, and south- 

 ward along the Rocky Mountains into the United States. Six 

 different writers have described new species of the genus Hes- 

 peromr/s, or white-footed mice, three of them being remark- 

 ably unlike anything previously known. Several of Baird's 

 species have also been revived as perfectly tenable subspecies. 

 Other genera of this large family present a similar history. 

 In short, not less than thirty species and subspecies have been 



1 " North American Fauna," No. 2, Oct., 1889, pp. 27-35, pll. ii.-vii. 



