Migrations of North American Birds. 189 
of Central Mexico, particularly its western slope and Cape St. Lu- 
cas, and it is an interesting fact that very few of the birds pecu- 
liar to the Western province are known to occur in Mexico at 
all. The North American winter birds of Western Mexico, as 
the Eastern province of North America, _ 
_ It may perhaps be proper to recall attention to the fact that, 
most of its species being common to the adjacent main land, 
it is hoped, impart much greater pe to the knowledge 0 
wide distribution in latitude, whether migrant, or residents, will 
= et to be larger the higher the latitude of their place of 
Irth, 
It is well known to zodlogists that of 
. . 
all animals, birds are the 
Most constant in their dimensions, so mu: d, 
ch so indeed, that size 
