MUSEUM OF COMPARATIVE ZOOLOGY. 167 



with much less power. Such at least is the general fact as indicated 

 by my own limited experience in Florida, which accords, I find, with 

 that of various other observers. 



In recounting the faunal peculiarities of Florida it is necessary to 

 allude further to a few facts that will be more fully presented in the 

 following chapters, namely, the differences which distinguish the Florida 

 representatives of species that have a wide distribution to the northward 

 from the northern ones. It has for some time been well known that a 

 difference in size in birds and mammals usually accompanies differences 

 of locality in respect to latitude and elevation. Other differences, how- 

 ever, are found to accompany these with considerable uniformity ; namely, 

 a relative increase in the length or general size of the bill, and an in- 

 crease in the intensity of the general color of the plumage.* Florida 

 birds, in short, usually differ considerably in these respects from their 

 New England cospecific representatives ; so much so, indeed, that in 

 many cases the majority of ornithologists would probably regard the 

 two forms as distinct species, though few of them have as yet been 

 specifically separated. 



Hence not only do birds of the same species living at distant points 

 differ considerably in size, color, and other features, but also in their 

 habits, notes, and songs. With the decrease in size to the southward 

 there seems to be a corresponding decrease in vivacity, — a fact which 

 accords with the general law of the distribution of the higher forms of 

 life in the temperate latitudes. Although a few structurally high types 

 are, from certain peculiarities of their conformation, necessarily tropical, 

 the highest races of men, whether considered physically, intellectually, 

 or morally, are inhabitants of a medium climate, and gradually decline 

 in rank both to the northward and southward from this favored re- 

 gion, animal and vegetable life reaching, as a whole, its highest 

 manifestation in the temperate latitudes. The excessive variety of 

 forms within the tropics mainly results from the addition of those 

 of comparatively low or medium grades, only a few of the exclusively 

 tropical forms being of absolutely high rank. Generally, too, the forms 

 to be properly regarded as temperate are represented in the tropics by 

 only their lower members, while, conversely, many of the higher types 

 of the tropics are really cosmopolitan. 



* See Annual Report of the Mus. Comp. Zool., 1669, p. 16. 



