1897. EXPEDITION TO CENTRAL AUSTRALIA. 259 



deposit. It is never more than fifty feet thick, and is interesting as 

 being the chief source of the Noble Opal so often obtained from 

 Australia. This mineral occurs disseminated through the rock in 

 minute fragments, though sometimes coating joints or fractures and 

 replacing wood and shells. 



Botany. 



The Report on the Botany is the work of Prof. Ralph Tate. So 

 far as systematic botany is concerned, he has been able to add eight 

 new species to science, to record sixteen species new to South 

 Australia, and 112 new to the Larapintine region. But the most 

 interesting portion of his Report deals with the geographical distribu- 

 tion of the plants observed, with the influence of the physiography of 

 the district on the present flora, and with the origin of the flora of this 

 region. The author has already contributed a valuable paper on this 

 subject, so far as it affects the whole continent, to the Australasian 

 Association for the Advancement of Science, and he had hoped that 

 in the McDonnell Range the explorers might find some of the pristine 

 flora of early Tertiary times, which had died out of the lower-lying 

 regions. In this, however, he was disappointed. Nevertheless, he 

 comes to some valuable conclusions largely confirmatory of his previous 

 views. These are briefly stated as follows. The Larapintine table- 

 land was isolated, except perhaps in a northerly direction, during the 

 deposition of the Upper Cretaceous beds. The marine submergence 

 was replaced by a lacustrine area, which continued during the early 

 Tertiary and into Pliocene times. During this period a cosmopolitan 

 flora prevailed. In Post-Pliocene times a high state of desiccation 

 was reached, which has continued till to-day. The cosmopolitan flora 

 has largely disappeared and its place is occupied by an oriental 

 immigration, more especially over the previously submerged areas. 



Thus the flora of the Larapintine region is a mixture of endemic 

 and immigrant (oriental) forms, and a most interesting statistical table 

 shows that a large percentage of the oriental forms have burr-Hke or 

 adhesive fruits rendering their immigration with that of animals 

 coming over the land-areas possible. 



It is unfortunate that Prof. Tate does not discuss more fully the 

 point already touched upon by Professor Spencer in the Narrative of 

 the Expedition relating to the spiny character of the plants making up 

 the scrub and desert flora. That a dry and arid climate requires some 

 modification of the plants will not be denied ; but to argue that the 

 spines have nothing to do with protection against animals, firstly, 

 because there are practically no animals in that region, and secondly, 

 because the camels the expedition introduced fed on the thorny acacia 

 as well as on the juicy Claytonia, will not settle the question. The 

 very absence of indigenous animals might be taken as proof that they 

 had been driven away by the protective adaptations of the plants, in 

 some cases by the spines and thorns, in others, such as the succulent 



