EUCALYPTUS TREES. 189 



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 UrviUea 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 

 Eremophila, with blossoms of manifold hue, decorate 

 the scrubs throughout the whole explored interior. 

 Among the desert Cassise two simple-leaved kinds are 

 remarkable. Of the Acacise, none here, except A. 

 Farnesiana, have pinnated leaves, and even one is 

 leafless ; the pinnated Acacias 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, 



