July, 1925 
The Queensland Naturalist. 
21 
worms. Tljo <jronp is represonted by worms which do not 
exceed an inch in len*»th, and althoiijrh they must be 
classed as ar|nalic their habitat is in the mud at the 
bottom of pools, wells or lakes. The modification of the 
setae and their approximation in form to those of the 
Mcftadrili, oj‘ terrestrial earthAcorms, may possibly be 
due to tlie nature of th(*ir habitat. Consecpiently in de- 
termining* their character as intermediate between those 
of the Microdrili and ^le^adrili, we do so for descriptive 
and not (genetic purposes: in other words, we do not 
necessarily regard them as forms Avhich have led the tvay 
from the Microdrili to Me«‘adrili. They might well be 
specialised descendants of such intermediate forms, and 
equally tvell tliey may in respect of these intermediate 
characters exhibit merely the results of a (’onvergent 
Evolution. It is so easy to be dogmatic in such matters, 
especially when the distribution of the forms concerned 
opens 11 ]) a vista of big ])rohlems. 
Tile history and distribution of the memlnu's of the 
grouj) are of very special interest. In 1895 T^eddard ob- 
tained from a subterranean well in New Zealand a new 
aquatic genus which he described under the name 
Phreodrilus. The form was so peculiar that it could 
not be included in any of the known families of this 
gronjA of worms. It was then found that forms which 
had been found in South America and tlie Falkland 
Islands, and had been desci'ilx^d undei' another name, 
belonged to the same genus. Since then a sj>ecial family 
has been created, to include these forms and others since 
described from various ])arts of the Soutliern 
TTemisphere. 
The family Piireodrilidae now includes the following 
genei’a : — 
Phreodrilus — Described by Beddard, and occurring 
in Falkland Islands, South America. New Zea- 
land, ('ampbell Islands, and Kerguelen Island. 
Pbreodriloides — Described by Benham, from Blue 
Lake, Mt. Kosciusko. 
Astacoiisidrilus — Described by Goddard, from the 
freshwater Crayfish Astaeopsidrilu.s, X.S.W. 
Tasmaniaedrilus— Described by Goddard. f]‘om Ben 
Lomond, Tasmania. 
Gondwanaedrilns — Described by Goddard, from 
Soulh Africa. 
