82 TRANSACTIONS 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 Rodentia” 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 
Muride, or the field rats and mice; the Saccomyide, or the 
pouched rats and mice; the Leporide, or the hares ; and the 
Sciuride, 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- 
peromys, or white-footed mice, three of them being remark- 
ably unlike avything previously known. Several of Baird’s 
species haye 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. 
