EUCALYPTUS TREES. 153 
are fixed. Some of these are not without their par- 
ticular uses. A few yield caragaheen, all bromine and 
iodine. Macrocystis pyrifera, the great kelp, which 
may be seen floating in large masses outside Port 
Philip Heads, attains the almost incredible length of 
many hundred feet, while a single plant of the leath- 
ery, broad Urvillea potatorum constitutes a heavy 
load for a pack-horse. 
The wide, depressed interior, once supposed to be 
an untraversable desert, consists, as far as hitherto 
ascertained, much less of sandy ridges than of sub- 
saline or grassy flats, largely interspersed with tracts 
of scrub, and occasionally broken by comparatively 
timberless ranges. The great genus Acacia, which 
gives to Australia alone about three hundred species 
(and, therefore, specific forms twice as numerous as 
that of any Australian generic type), sends its shrubs 
and trees also in masses over this part of the country, 
where, with their harsh and hard foliage, they are 
well capable to resist the effect of the high tempera- 
ture during the season of aridity, while they are 
equally contented with the low degree of warmth to 
which, during nights of the cool season, the dry at- 
mosphere becomes reduced. Handsome bushes of 
Kremophila, with blossoms of manifold hue, decorate 
the scrubs throughout the whole explored interior, 
Among the desert Cassis two simple-leaved kinds are 
remarkable. Of the Acaciz, none here, except A. 
Farnesiana, have pinnated leaves, and even one is 
leafless ; the pinnated Acaciz being restricted to the 
more littoral tracts, and even there from the Great 
Bight to Guichen Bay entirely absent. If shelter 
plantations of the rapidly-growing Eucalypts, Acacias, 
