July, 1925 
The Queensland Naturalist. 
25 
genetic iinportanee are as restricted to the North- 
ern Hemisphere, and thus we are led to conclude that 
each group has been evolved in the respective hemi- 
spheres, That being the ease, we might then regard the 
-existing members of the family as the descendants of au 
.ancient Phreodrilid ancestor, Avhich might have 
flourished as early as, if not earlier than, Permo-Carboni- 
ierous times on ancient Gondwanaland. 
The interest attaching to these comparatively in- 
significant forms indicates that a great deal of informa- 
tion about our Aiistralian Invertebrate fauna still awaits 
the naturalist and biologist. This particular division of 
oiiv fauna has so far been studied in detail by one worker 
only — T refer to the aquatic OHgochaeta. Naturally, 
larger forms have attracted tlie attention of naturalists, 
but this brief address may serve to sIioav that great re- 
sults may repay the efforts of the naturalist who in- 
terests himself in the invertebrae fauna. There is no 
continent which should hold greater attractions for the 
naturalist than Australia. The small groiij) on Avhieh I 
have touched has as yet been hardly scratched, and yet 
it represents only a very small portion of our inverte- 
brate stock, and only a small fraction of the many in- 
teresting primitive invertebrate fauna of the Southern 
Continents. 
The forms mentioned in this address raise the pro- 
blem of the past relations of Australia to the other con- 
tinents, Many Australian animal forms constitute classic 
references used in support of this or that theory of lainl 
connections. In this direction there has been a tendency 
to assume, because the distribution of certain forms 
satisfies the demands of a particular theory that that 
theory has been proved. In this way there lias been de- 
veloped a someAvhat unscientific mode of attack on the 
problem, and the conclusions attained must yet be con- 
sidered more or less ai'bitrary. Il has become the ])rae' 
tiee to too frequently limit the relationshij) of forms on 
;an assumed genetic basis to observations of a purely 
morphological character, and this criticism applies to the 
procedure whether fossil or living forms are concerned. 
The unfortunate tendency in this connection is that we 
arbitrarily simplify the vagaries and complexities of an 
■cAmlutionary process and dive for a certain point whicli 
Ave wish to reach. In following the distribution of 
particular forms of life we are guided by the geographi- 
