10 
America, Humboldt estimates them as ? \ ; and in New 
Holland as B \. They decrease again in proportion as we 
approach towards either pole, so that in France they are 
only sV, in Portugal in the Greek Archipelego 5 J 7 , 
and in Egypt y} T . Northward of these countries their 
proportion again augments, so that they form J T of the 
Phsenogamous vegetation of Scotland, ^ in Sweden, ^ in 
Iceland, ^ in Greenland, and ^ at North Cape. No ferns 
have yet been discovered in the most northern parts of the 
arctic zone, as is shown by the catalogues of plants from 
Melville's Island and Spitzbergen. It appears from the 
observations of Dr. Hooker that where ferns prevail flow- 
ering plants are less abundant, and vice versa ; which he 
illustrates by a comparison of the vegetation of Tasmania 
and New Zealand. The former of these islands, barely 
250 miles long, contains four times as many species of 
flowering plants as New Zealand, whose total length is 
900 miles. On the other hand, this latter country possesses 
more than four times as many kinds of fern as Tasmania. 
In New Zealand he collected 36 species of fern, in an area 
of only a few acres, which presented scarcely a dozen flower- 
ing plants besides ; while an equal area in the neighbour- 
hood of Sydney, (in the sa,me latitude) would have yielded 
upwards of 100 flowering plants, and but two or three ferns. 
" The total known number of existing species of ferns at 
the present day is probably 1,500, whose geographical distri- 
bution is about the following: — 1. Those of the temperate and 
frigid zone of the northern hemisphere, about 144 species. 
2. Those of the southern temperate zone, including the 
Cape of Good Hope, parts of South America, and the 
extra-tropical part of New Holland, and New Zealand, 140 
species. 3. Those which grow within 30 or 35 degrees on 
each side of the Equator, 1,200 species.*" 
* Buckland's Bridgewater Treatise, p. 462. 
