INTRODUCTION. xlix 
what limits others are restricted, may be gathered from the various tables and para- 
graphs in the Appendix, more especially from those paragraphs on the distribution of 
the more prominent natural orders (vol. iv. pp. 235 to 282), and from the analysis 
of a sample of the mountain vegetation (p. 298); but it may be of interest to illus- 
trate this further by a few examples, selecting such groups as are spread over the 
tropical, or subtropical, and temperate parts of the country. 
Foremost among the types not extending into Chili are the Melastomacee ; but their 
absence can hardly be explained by climatal conditions alone. The large genus Cuphea, 
which ranges from the south-eastern states of North America to Uruguay and Chili, 
is represented in the last country by only one species (C. spicata), which covers nearly 
the whole area of the genus. Juchsia extends from Mexico to Magellan’s Straits, is 
represented in San Domingo by two species, and by three or four species in Brazil, 
and it reappears in New Zealand. The Turneracee are essentially temperate and sub- 
tropical plants of the western side of the continent, yet there are a few species in 
Brazil and Buenos Ayres. The specially characteristic Cactacee are spread all over 
South America and the West Indies, though they do not inhabit all districts. Their 
northern extensions are given in detail in the fourth volume, page 247. The Brome- 
liaceee are spread all over South and Central America and the West Indies, and 
penetrate the south-eastern states of North America. The more tropical Cyclanthacee, 
Marcgraviacee, Vochysiacee, and Myrtacee-Lecythidee are mainly eastern South 
American, though they are also represented in Central America; and the distribution 
of such genera as Tropeolum, Baccharis, Coccoloba, Lacistema, Roupala, Lisianthus, 
Hyptis, Philodendron, Anthurium, Brassia, Dichea, Epidendrum, Oncidium, and many 
others proves that we have to deal with one large primary region. Epiphytal orchids 
generally are local, or occupy relatively small geographical areas, yet many of the 
American species have a considerable range. A list of thirty Mexican species with 
their distribution is given in the fourth volume of this work (p. 270), and it may be 
added here that about eighty of the Mexican species extend to the West Indies, and 
upwards of 100 to South America, many of the species being the same in the three 
areas, as is apparent from the fact that 800 out of 938 are endemic in Mexico. So far 
as the distribution*is known, a larger number of the Mexican species reach Brazil 
than Peru. Approximately the numbers are :—Colombia (New Granada and Ecuador) 
seventy-five species ; Peru twenty-two; Guiana forty-five; and Brazil thirty-six *. 
Wallace divides his neotropical zoological region, which corresponds to our South- 
American region, into four subregions, namely a Mexican, an Antillean, a Brazilian, 
* In the discussion on the northern limits of epiphytal orchids in Mexico (vol. iv. p. 269) the improbability 
of Meiracyllium gemma and Odontoglossum madrense being North Mexican was advanced, though in conse- 
quence of the habitat being given as Sierra Madre they were 80 recorded. It appears, however (Veitch, 
Odontoglossum, p. 51), that they were found in the neighbourhood of Colima, in about 19° N, lat., and far 
from the Sierra Madre, in Durango, where Seemann collected. 
BIOL. CENTR.-AMER., Bot. Vol. I., October 1888. - g 
