f 
- the southward included not only those instances noticed by Pro- 
. tints on the Pacific coast north of latitude 40°, and light colors 
these general facts with the relative amount of aqueous prec! 
228 ZOOLOGY. 
Generalization “1” of Mr. Ridgway’s enumeration refers to 
variation in size with locality, and is a law which was most 
uneqtivocably established by Professor Baird. Generalization 
“2” refers to the enlargement of the Dill in Florida and cape St. 
Lucas birds, while generalization “3” refers to the ‘longer tails 
of western birds than of eastern examples of the same spe- 
cies.” Generalization “4” refers to color, and will be presently 
noticed more in detail. In respect to generalizations “2” and 
“3? Professor Baird only refers to the disproportionate enlarge- 
ment of the bill and tail at certain localities, as noteworthy facts, — 
and, so far from explicitly stating them as general laws, he says 
in a foot-note, referring to the increased size of the bill, ‘This dis- * : 
proportionate difference of size at cape St. Lucas and south Florida 
is probably connected with the limited range of the species in those 
regions, which have thus an insular rather than continental relation- 
ship ;”* thus apparently looking upon these variations as local 
phenomena. Neither in the case of the enlarged bills, nor the 
lengthened tail, does he hint at any general geographical law of 
variation of which these are simply the expressions, whereas my ee 
announcement of the law of the enlargement of peripheral parts 0 ; 
fessor Baird, but a multitude of others I had myself observed, both 
among mammals and birds, and at numerous localities in addition 
to Florida and lower California. In respect to the tail it was Im- 
creased in length at the southward—not at the westward— in 
accordance with the above law to which I called attention. i 
As regards laws of color variation, Professor Baird -merel 
makes the general statement that “specimens from the Pacific 
coast are.apt to be darker in color than those from the interior, the 
latter frequently exhibiting a bleached or weatherbeaten appear- 
ance, possibly the result of greater exposure to the elements and 
less protection by dense forests,” whilst I announced a regton. of 
more rufous tints in the middle portions of the continent, darker 
from the arid plains and deserts, as well as the law of increased 
intensity of color to the southward; at the same time cnr - 
* Amer. Jour. Sci. and Arts, 2d series, vol. xli, p. 191. 
į Amer. Jour. Sci. and Arts, 2d series, Vol. xli, p. 192. 
