C. H. TYLER TOWNSEND-BIO-GEOGRAPITY OP TEXAS. 
93 
SYNOPSIS OF THE LIFE DIVISIONS OF AMERICA. 
Referring to the tabular synopsis, it will be seen that all America is 
divisible into five grand divisions, which should be known as regions. 
Each of the American continents is divisible into three broad temperature 
belts or regions, running in a general way with the isothermal lines of 
greatest heat in summer, least heat in winter, and total of effective sensi¬ 
ble temperatures for the year. These three belts are best characterized 
by the adjectives boreal, temperate and tropical. I have thus designated 
the five regions as the Boreal, Neotejiperate, Neotropical, Austro- 
temperate, and South Boreal. Only two of them, the first and the 
last, extend outside of America. A certain extent of the northern por¬ 
tion of North America, as is agreed by prominent writers on geographic 
distribution, can not be considered other than a circumpolar region. 
Some favor considering only the circumpolar Arctic zone (see tabular syn¬ 
opsis) as forming the region, and give it the name of the Arctic region. 
But this is too circumscribed an area, without a sufficient number of 
the forms of life and with no diversity of distribution, so that it would 
be incapable of subdivision into zones or provinces. Others favor uniting 
the whole temperate and boreal area of the northern hemisphere into one 
region. But this, on the other hand, contains too many diversities of 
distribution and would prove too unwieldy and misleading. I have there¬ 
fore adopted a mean between the two, which moreover indicates more 
truly than can any other classification the actual distribution of life in 
the northern hemisphere. It is wholly unnecessary to go into the reasons 
which support this view, as the field has been well discussed from all 
standpoints by a score of writers—Sclater, Wallace, Cope, Packard, Allen, 
Merriam, Gill, Osten, Sacken, and many others. 
The nomenclature adopted in this paper for the regions is the result of 
an effort to employ the Wallace-Sclaterian terminology so far as it har¬ 
monizes with the facts of American biogeography. I should state here 
that the terms Nearctic and Palaearctic have long since been discarded 
as misnomers by American writers. Besides the unfortunate application 
of the terms, the division between the regions does not accord with the 
facts of distribution, and thus there is double reason for dropping the 
names. But I believe that the Sclaterian term Neotropical is eminently 
available for the purely tropical portions of America, and, moreover, I 
believe that the preservation and use of this term are highly advisable. 
It is absolutely correct, and can not be misleading when accepted in its 
proper meaning of a purely tropical region. Sclater’s neotropical in¬ 
cluded also temperate South America, but that is no reason why we 
should sink a comprehensive and valuable term when we can properly 
