189].] :N"EW YORK ACADEMY OF SCIENCES. 83 



added during the last six years, nearly doubling the number re- 

 cognized in 1877. 



Of the squirrels, Baird admitted thirty-nine species — an 

 enormous reduction, by the way, from the number recognized 

 by Audubon and Bachman. In 1877 I confirmed Baird's pre- 

 vious reductions, and still further reduced the number to thirty- 

 three species and subspecies, adding, however, eight to those 

 recognized by Baird. Since 1877 a large number of species 

 and subspecies has been added, mainly among the ground squir- 

 rels and spermophiles. These additions are based ou almost 

 wholly new materials, and include species as distinct from their 

 nearest allies as any previously known. That is, they are not 

 the result of a new way of looking at things, but are actual dis- 

 coveries of forms not at all closely related to anything known 

 before. 



Of the Saccomyidte, Baird in 1857 recognized nine species; 

 Cones, in 1877, admitted the same number. This group dur- 

 ing the last four years has been thoroughly revolutionized, 

 mainly by Dr. Merriam.^ The names of several of the old 

 species have been shown to have been strangely misapplied; one 

 new genus and a new subgenus, and some twenty or more new 

 species, have been added, besides numerous subspecies. Among 

 the new forms are some strikingly different from any known to 

 either Baird or Coues, while others differ in only comparatively 

 slight particulars. These animals are peculiar to the arid plains 

 and deserts of the West; are nocturnal and somewhat subterranean 

 in their habits, and seem, moreover, especially susceptible^to the 

 influence of conditions of environment. Owing to their peculiar 

 habits, and to the fact that the area they inhabit has been, till 

 lately, little explored, very few specimens were extant in collec- 

 tions up to a very recent date. 



Of the Leporidae, or hares, Baird in 1857 was able to recognize 

 but thirteen species as ^orth American. All but one of these 

 were admitted by me in 1877 and two others were added. Within 

 the last year five others have been recognized, three of which are 

 very distinct from any previously known, while two are old ones 

 revived as subspecies. 



To what, then, is all this change due ? To several very ob- 

 vious causes. First, to a vast increase of material; second, to its 

 greatly improved quality; third, to more thorough and intelli- 

 gent work in the field, conducted on a tenfold greater scale 

 than ever before. Thousands of specimens are taken now where 

 formerly only a few scores were obtained. Collecting and all 



1 " North American Fauna," No. 1, Oct., 1889; ibid., No. S, Sept., 1890, 

 pp. 71-75; and ibid., No. 4, Oct., 1890, pp. 41-49. 



