July, 1925 
The Queensland Naturalist. 
n 
bability of their common ancestral stock, or as the result 
of their inability of carrying on the struggle for exist- 
ence in habitats whei’e other forms of Oligochaeta. etc., 
find faA^ourable conditions, 
Tlie question now arises, whether the Phreodrilidae 
enjoyed at one time a much wider distribution, and have 
sinc<^ disappeared in most parts, or whether we are to 
regard them as forms which made their appearance in 
the Southern Hemisphere. 
Now it is interesting here to note that although 
none of the group is known in the Northern Hemisphere, 
yet in that region there occurs a family- — Lumhrieulidae — 
which is unknown in the ^Southern Hemisphere. Further^ 
this latter family occupies a position of the same phylo- 
genetic status as do the Phreodrilidae between the two 
main divisions of the Oligochaete worms, and this is* 
significant Mdien their res]>eetive restricted distributions 
are considered. Both may have arisen, and no doubt did 
originate, from a common stock, and it seems highly 
jirobable that they have been evolved in the region now 
occupied by them. That there has been no intermingling 
of the two races, and no sjireading into tlie other hemi- 
sphere bj^ either of them, and the fact that both have 
a circumpolar distidbutioii, must signify a close asso- 
ciation of the land areas of the Northern TIeniispliere 
at some period, and a corresponding intimate relation 
between the continents of the Southern Hemisphere. 
Otherwise it is hard to understand why two such groupvS 
should have such a complete circumpolar distribution 
in their respective hemispheres. 
Possibly the Phreodrilidae have been pi’eserved for 
us on the tops of the mountains, and apparently in abun- 
dance in South Africa, as living relics of the fauna 
which flourished in that old land area — Gondwanaland — 
which once linked up our Southeni continents, stretching 
across the Atlantic and Indian Oceans. Tf we can re- 
gard their adaptation to low temperatures as a com- 
mon ancestral character, they may be forms whose dis- 
tribution was greatly lielped in a circum]>olar direction 
])y the glacial conditions which obtained during the time 
of existence of Gondwanaland, 
These remarks may be construed as signifying one 
of two conclusions: — 
