Affınities: Bermuda Islands. 331 
not hitherto recorded from North America. Most of the foregoing are represented 
in North America by closely allied species, and there are twenty-two North 
American plants which are apparently indigenous in the Bermudas, but do not 
extend to the West Indies. 
Of the 144 species comprising the indigenous flora, some 46 are widely 
dispersed, by which is meant that, independently of their distribution in the 
New World, they extend to some part of the Old. 
As compared with other islands in similar and different latitudes and simi- 
larly situated to the nearest continents, the flora of the Bermudas is singularly 
poor in endemic species. The endemic element in the flora of the islands 
is limited, as far as known, to ıı species, namely, Juniperus bermudiana, 
Galium bermudianum, Eriseron Darrellianus, Statice Lefroyi, Sisyrinchtum 
bermudianum, Sabal Blackburniana, Carex bermudiana, Adiantum bellum, As- 
plenium Laffanianum, Nephrodium bermudianum and a moss Tortula bermudiana. 
7. Southern Extension of North American Flora. 
Relationship of North and South American Floras. The relationship of the 
floras of North and South America will be discussed under the following heads: 
ıst, the Gulf neo-tropic, and, the alpine and arctic-alpine and z3rd, the warm 
temperate and semi-tropic xerophilous elements embracing (a) high plateau and 
mountain forms of the transition and upper Sonoran climatic zones; (b) enclosed 
basin and valley forms of the lower Sonoran climatic zone; (c) semitropic 
xerophilous forms of Gulf distribution. It should be mentioned that the terms 
transition, upper Sonoran and lower Sonoran, proposed by MERRIAM, are used 
here in the sense of areas controlled by the same climatic conditions and not 
as defining phytogeographic regions, which according to the writer are not 
dependent altogether upon the temperate control of plant phenomena, but upon 
rainfall, relation of rainfall to evaporation, physiography and the historic element. 
According to BrRAY »), the Gulf territory includes those regions which have had 
a common history in the development of their flora during the fluctuating 
geologic conditions of the Gulf area. While this zone is but a part of the 
greater neotropic, its association with a common sequence of geologic changes 
has as ENGLER thinks, given it a degree of distinctness from the Brazilian region. 
The regions so associated are: The coast lands, plains and sub-Andean parts of 
Guiana, Colombia and Venezuela; the Central American region except the tierra 
templada, the tierra fria of Guatemala and the isolated elevations (above 
8000 feet) in Nicaragua and Costa Rica; the tierra caliente of Mexico which 
On the west reaches northward to include the lower Colorado Valley in Cali- 
fornia and Arizona, and embraces the point of the lower California peninsula, 
and on the east coast is a narrow belt extending northward to the lower Rio 
Grande Valley in Texas, the lower third of Florida and the Greater and Lesser 
1) Bray, W.L.: The Relations of the North American Flora to that of South UNO 
Seience new ser. XII: 712. Nov. 9, 1900. 
