Tea Loy [ Allen. 
~ 
general law of the decrease in size with the decrease in latitude, 
established some years since by Prof. Baird, in his elaboration 
of the materials collected by the different vovernment surveys for a 
Pacific railroad route. Mr. Allen also called attention to the differ- 
ences in the character of the pelage of mammals in individuals of 
the same species inhabiting northern and southern localities, those at 
the north as a general rule, having a thicker and softer coat, and 
more heavily clothed feet; and to the greater development at the 
southward of peripheral parts, as the ears and feet, especially the 
former. fi 
In respect to birds, it was shown that not only the same law of 
diminution in general size to the southward obtains in this class as 
in mammals, but that there are other strongly marked coincident 
variations, affecting not only color but structural peculiarities. It 
was stated that, as a general rule, birds of the same species are much 
darker at the southern than at the northern borders of their re- 
spective habitats. 
Mr. Allen showed that the bill and tail gradually increase in size 
to the southward, frequently to a very marked degree, the differ- 
ences in this respect being inverse to the difference in the general 
size of the individuals. While the total length of the bird may be 
considerably less at the southward, the bill and the tail often become 
actually longer; but variation in this respect is more especially notice- 
able in long-billed and lone-tailed forms. There is also a noticeable ten- 
dency to an elongation of the claws to the southward, particularly that 
of the hallux, which is markedly apparent in the genus Pipilo, as well 
as in other genera. In P. erythrophthalmus the differences in this re- 
spect between Massachusetts and Florida specimens is quite marked. 
The same fact is true in respect to the western forms of this genus, 
where the difference between specimens from Washington Territory 
and Lower California is greater than is seen in the Pipilos of the 
Atlantic States. 
The differences in color between specimens of the same species 
from the interior of the continent, as compared with those from the 
Atlantic coast, and from the Pacific coast north of California, were 
also noticed, and specimens from the Cambridge Museum of Com- 
parative Zoology were shown, illustrating not only the paler tints of 
those from the Great Plains and the interior of the continent gener- 
ally, but also the greater intensity of color at the southward along 
the Atlantic seaboard, as well as the coincident differences in the size 
and form of the bill and inother features. Attention was particularly 
