250 : JOURNAL OF SCIENCE, 
Now in dealing with this part of our fauna and flora, we have 
to take into consideration two means of dispersal, at present 
going on, which are not found, or only to a very limited extent, in 
the tropical parts of the ocean. In the first place the almost 
constant westerly winds travelling round the globe in high 
southern latitudes, cause an easterly current which must neces- 
sarily drift to great distances the detached masses of kelp which 
are commonly seen floating in these seas, and the kelp might 
easily convey marine crustacea and mollusca with it. In the 
second place, the larger petrels range widely over the southern 
ocean, and might sometimes carry seeds in their plumage. I 
leave icebergs out of consideration, for they would not assist 
marine animals in migrating, and I do not see how any of our 
insects or fresh-water fishes, or the seeds of any of our flowering 
plants could get upon them. Capt. Cook thus describes the 
vegetation of S. Georgia, between Lats. 54° and 55° S. :—“ Not 
a tree was to be seen, not a shrub even big enough to make a tooth- 
pick. The only vegetation we met with was a coarse strong- - 
bladed grass, growing in tufts, wild burnet, and a plant like moss 
which sprang from the rocks.”’* No flowering plant has been 
found south of 62° S. The most southerly land on which vegeta- 
tion occurs is Cockburn Island, one of the South Shetlands, in 
Lat 64° 12’ S., and here there are but a few mosses and lichens, 
Sir J. Hooker landed on Possession Island, in 71° 56’ S., and on 
Franklin Island, in 76° 8° S., and did not find a fragment of 
vegetation on either 
But if marine currents, petrels, and the wind have been the 
only, or indeed the chief means of transport, we ought to find 
that the diffusion of plants and animals bears some relation to 
the distances of the land masses from each other. Now the dis- 
tance of S. Africa from Tasmania is about the same as that of 
New Zealand from S. America, and between Africa and Tasma- 
nia there are several possible halting. places, so that we should 
expect that the connection of New Zealand with S. Africa, 
brought about by these means, would at any rate be nearly as 
ereat as that between New Zealand and Patagonia. This is 
really the case in our marine fishes and marine mollusca ; in 
each of which about the same number of species belong to S. 7 
Africa as to S. America, while about six times as many are found © 
in Tasmania, which is about one-fifth of the distance ot Patago- 
nia, and one-sixth of the distance of the Cape of Good Hopen® 
But such is by no means the case in the marine crustacea, for ~ 
here as many of our species are found in S. America as in AUus-9§ 
tralia, while only one-third of the number occur in S$. Africa. 
The species of flowering plants common to. New Zealand and ~ 
Antarctic S. America are three times as many as those common 
to New Zealand and S. Africa. ‘The species of Antarctic flower- a 
* Voyage Round the World, 1772-75, Vol. IL, p, 213. r 
+ Icebergs are said to be formed in the Gulf of ‘Penas, in Chili (Lat. 47°S.), but | 
such an isolated occurrence need not be taken into account in the dispersal of pa ‘ 
for these icebergs could not drift far without melting, 
