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MEETINGS OF SOCIETIES. 87 
small barbs at their-apex, and the fruit thus adheres very readily ; 
the genus is confined to the Southern Hemisphere, except in 
America, where it has spread as far as Mexico and California, and 
in Polynesia as far as the Sandwich Islands. The occurrence ot 
the barb is a very peculiar feature in the New Zealand species. 
The common pivi-pirt (A. sanguisorbe) is a native of Australia, 
Tasmania, and Tristan d’Acunha, as well as New Zealand, and 
the calyx-spines are always barbed. A. adscendens, another barbed 
species, occurs also in Fuegia and the Falkland Islands, while 
A. nove zealandie, a third barbed species, though cndemic, is alto- 
gether too near A. sanguisorbe to rank as an exception. The other 
four species are also endemic, and of these A. depressa bears barbs, 
while the other three, A. microphylla, buchanant, and inermis are 
almost entirely without them. The barbs, while no doubt of use 
in adhering to the feathers of birds, are best fitted to stick to the 
hair and skin of vassing animals, and I think that in these smooth- 
spined Acenas we have a case of loss of an organ through disuse. 
The other specially furnished genus is Uncima, sedges which 
occur chiefly in the Southern Hemisphere, but range ‘as far north 
as the mountains of Abyssinia. The seed in every species is fur- 
nished with a long hooked bristle, which springs from the base of 
the nut, and projects out of the utricle or sac enclosing the fruit. 
; Our species are mostly endemic, but one is almost identical 
with a Fuegian species, and one or two with Tasmanian forms. 
It appears to me probable that the singular Chatham Island lily 
(or forget-me-not), Myosotidium nobile, is derived from an originally 
barbed plant, and that by long isolation it has lost the barbed 
bristles on the nuts characteristic of the Australian genus Cyno- 
glossum, its nearest allies, just as it has lost the hispid character 
considered so distinctive of other Bovaginee. 
The last mode specified in which birds carry seeds is attached 
to the mud or earth which clings to their feet. This subject has 
already been so carefully and conclusively worked out, particularly 
by Mr. Darwin in ‘“ The Origin of Species,” that I need not do 
more than refer to it. Sir J. D. Hooker, in the recently-published 
(1879) account of the botany of Kerguelen Island (Challenger 
Expedition Reports), considers that the few species of flowering 
plants of that island, presenting, as they do, a decided Fuegian 
facies, have been thus brought by land birds. These are very 
abundant on the Falkland Islands, where the vegetation is 
identical with that of colder South America, and favoured by the 
prevalent westerly gales, and the numerous stepping-stones, 
probably in the form of islands formerly existing, these land birds 
have probably found their way to Kerguelen Island. And he goes 
on to say that ‘‘ the absence of such birds from the present avi- 
fauna of the island offers no obstacle to such a speculation, as 
such immigrants would on arrival speedily be destroyed by the 
predatory gulls and petrels of the island.” It is probable that 
some of the antarctic and South American torms occurring in New 
Zealand, and also in Tasmania and South-east Australia, have 
been thus introduced. And this probability is increased, it we 
assume, with Mr. Wallace, that changes similar to those which 
have occurred in arctic regions have also taken place in the 
antarctic—viz., that great alternations of climate have occurred in 
past ages, during some of which the now ice-clad antarctic conti- 
