140 MR. А. D. COTTON ОМ CRYPTOGAMS 
Wickham Heights run almost due east and west across the East Island, the 
highest peak being Mount Usborne, 2245 feet. The climate is bleak and 
the penetrating power of the wind extraordinary ; but the temperature is 
fairly equable, ranging from 19° F.-42? Е. in winter and from 34° F.-72? Е. 
in summer. 
“ Up to comparatively recent times the descendants of the cattle landed by 
Bougainville on the East Island and those landed by sealers and others on 
the Western Island rambled everywhere, but, owing to their comparatively 
small numbers, they did not appreciably affect the flora. About the year 
1867 sheep were introduced, and with them came Scotch shepherds. With 
their régime a rapid change took place over the whole archipelago and whole- 
sale burning of the ‘ heather? (Æmpetrum rubrum) and grasses followed every 
spring-time. 
« When the late Mr. W. W. Bertrand first settled on the West Falklands 
the grass on the plains was waist deep, and whole flocks of sheep would 
disappear into hidden brooks and streams which were effectually concealed by 
this rank vegetation. Darwin’s statement (* More Letters,’ vol.i. р. 380) that 
the ‘struggle for existence of plants with hostile animals is of supreme 
importance’ is very plainly illustrated on the Falkland archipelago flora. 
Sheep deteriorate and eventually destroy the pasture-lands over which they 
graze, and this fact is very apparent when one follows пр a vast flock while 
feeding. They pull up whenever possible the tufts of the finer grasses by the 
roots, and orchids and Tussac grass аге eaten down to the ground, in the case 
of the former plants the bulbous roots being even devoured, so that it is useless 
to look for plants in the sheep-paddocks. Sheep also nibble the young shoots 
of Chiliotrichum amelloideum and Veronica elliptica, destroying in places 
whole valleys of the former to which they have access. The delicate agarics 
are nearly all to be found in the shelter of the former shrub in deep valleys 
rich with humus. 
“ Most of the lichens were collected in the uplands near Roy Cove at a 
height of about 150-300 ft., where foliaceous and fruticolous species abound. 
One of the most interesting is Parmelia lugubris, which is found in great 
abundance where Empetrum covers the hills. When moist it is a very 
delicate green and black underneath with brown tips, when dry the green 
pales and it is practically black and white. Owing to its hollow thallus 
inflated with air, detached pieces are carried for miles by the wind, and it is 
thus plentiful all over the uplands. Cup-lichens (Cladoniw) are especially 
common on burnt or half-burnt bogs. The foliaceous forms (species of 
Parmelia and Sticta) are often much injured by sheep, so that great difficulty 
is experienced in obtaining perfect specimens. Even on exposed summits, 
such as Rame Head and Mount Adam, a very Juxuriant lichen vegetation 
exists, the beautiful Neuropogon melaxanthum being particularly fine and 
forming a veritable miniature forest. 
