1874.] 277 [Allen. 



in respect to both mammals and birds. The occurrence of variations 

 in the proportion of parts and in color at certain localities among in- 

 dividuals of the same species, was also at the same time brought to 

 notice, and again alluded to by Prof. Baird in 1866. These observa- 

 tions led to a further examination of this interesting subject, and the 

 discovery of hundreds of additional facts of a similar character. The 

 instances noticed prior to 1866 proved to be by no means exceptional 

 cases, but to be the result of other geographical laws of variation, as 

 universal and almost as well pronounced as that of the variation of 

 size with locality. These I have termed the laws of (1) the enlarge- 

 ment of peripheral parts at the southward; (2) of the increase in 

 intensity and extent of dark colors at the southward, and (3) 

 increase of color with increase of humidity, or the correlation of in- 

 tensity of color with the mean annual rainfall. 1 I now propose to re- 

 fer more especially to the variation of color with locality among the 

 North American SciuridcB, and to briefly notice some of the results 

 that have attended a recent examination of the group. 



First, in respect to the increase in intensity of color from the north 

 southward. Among the squirrels this increase is finely illustrated in 

 Sciurus hudsonius and in Tamias striatus, representatives of which 

 from the southern parts of New York and Pennsylvania are much 

 more highly colored than are those from northern New England and 



i See Bull. Mus. Coxnp. Zool., Vol. n, pp. 229-242, 369-375, April, 1871; — Ibid. 

 Vol. in, pp. 114-119, July, 1872. Also, Proc. Bost. Soc. Nat. Hist., Vol. xv, pp. 

 156-159, Sept., 1872 (Communicated Apr. 17,1872) ; — Ibid, xv, pp. 212-219, Dec, 

 1872 (Communicated June 19, 1872); — Amer. Nat., Vol. VI, pp. 559-560, Sept., 1872. 

 For other reference to the subject see Coues (Dr. Elliott), Proc. Acad. Nat. 

 Sci., Phila., 1872, p. 60, July, 1872; Bjdgway (Robert), Amer. Journ. Arts 

 and Sci., 3d Ser., Vol. iv, pp. 454-460, and Vol. v, pp. 39-44, Dec, 1872, and Jan., 

 1873 ; containing a further development of the subject of geographical variation in 

 color, and the addition of many new corroborative facts. Also the critique of Dr. 

 Coues, on Mr. Pddgway's article (Amer. Nat., Vol. vn, pp. 415-418, July, 1873), and 

 Mr. Pddgway's reply (Ibid., pp. 548-555, Sept., 1873). 



In this connection I feel called upon to notice briefly Mr. Pddgway's important 

 paper in the American Journal of Arts and Science, and his defence of it in the 

 American Naturalist. In respect to the original article, the general laws of geo- 

 graphical variation in color, previously worked out by others, are here restated 

 without any intimation whatever that anything had been previously done on the 

 subject. The ample apology, however, subsequently made, renders it clear that 

 this omission was an inadvertance rather than any intended wrong, and would not 

 be here alluded to except for its historical connection with a matter now to be 

 noticed. In his reply to Dr. Coues' rather pointed criticism, his anxiety to exon- 

 erate himself, seems (to me, at least,) to have misled him into a somewhat unfair 

 statement of the points at issue as respects the originality of some of my own work. 



