sea lilies, starfishes, etc. — clark. 7 



Echini. 



Phyllacanihus magniflcus. 

 Centrostephanus tenuispinus. 

 Peronella aphnostina. 



HOLOTHURIANS. 



Caudina tetrapora. 

 Colochirus axiologus. 



It is useless to speculate on the origin or significance of this 

 West Australian fauna until we know the fauna of the 

 north-western coast. The region between Shark Bay and 

 Torres Strait should be thoroughly explored, and, as soon as 

 possible, that between MelviUe Island and Timor. When this 

 vast area is as well known as South-eastern Australia we shall 

 be able to form an intelligent opinion concerning the West 

 Austrahan subregion. We shall know then, too, whether we 

 ought to recognise a North AustraHan subregion, and if so, 

 whence its fauna came. There are some very characteristic 

 species from that district, but they do not come within the 

 scope of this report. 



So far as the present evidence goes, it seems that the Western 

 Austrahan fauna is a derivative of that of the South Aus- 

 tralian subregion with a considerable element from the 

 tropical Indian Ocean. The characteristic South Australian 

 fauna is clearly derived from that of the east coast with at 

 least a small addition from a southern fauna common to South 

 Africa and southern South America. The exact extent and 

 significance of this southern element is one of the most 

 interesting and least known features of the South Australian 

 fauna. There is little question that the East Australian 

 fauna is derived directly from the Indo -Pacific and is still 

 closely associated with the fauna of the East Indies and the 

 Pacific Islands. Whether any of the east coast fauna has 

 been received through Torres Strait or whether it has all come 

 around the eastern end of New Guinea, or whether it is largely 

 of southern origin and has spread northward and eastward, 

 are still questions to be answered, but I see very little evidence 

 indeed in favour of the latter view. 



In the above discussion, I have obviously omitted all 

 reference to other groups of animals, believing I could best do 

 my part in the solution of the problem by presenting simply 

 the evidence offered by the group I am studying. I believe 

 the Echinoderms are a very satisfactory group by which to 

 test possible lines of migration, the great antiquity of the 

 phylum, the relatively small number of genera and species- 



