238 Transactions of the Boyal Society of South Africa. 
Gondwanaedrilus Spermathecae distinct, but ducts communicating 
with male penial chamber. 
Tasmaniaedrilus Spermathecae evanescent and ducts absent. 
Wall thin and non-glandular. 
Phreodriloides Spermathecae and ducts absent. 
It will be seen that we have now an undoubtedly complete anatomical 
series, and that the family w^hich at first known only by the genus 
Phreodrilus was considered so unique in regard chiefly to its setae and 
spermathecae, can be split into genera whose most marked dilferential 
characters concern both these structures. 
Again, it is quite clear that Phreodrilus with its well-developed spermi- 
ducal gland, glandular spermatheca, and spermathecal ducts opening 
directly to the exterior, approaches more closely than any of the other 
genera to the ancestral Phreodrilid stock. 
Eemarks. 
The distribution of the family has been very interesting up to the 
present time • in view of the limitation to the southern portion of the 
Southern Hemisphere, and also of its restricted habitat in these regions. 
That the group does possess a great phylogenetic value will, we think, 
be conceded by all workers on the Oligochaeta, and the fact that their 
occurrence in South Africa and further in the mountainous region only 
was deduced by one of us several years ago is, at least, not inconsistent, 
with this idea. 
The fact that the well-searched parts of the Northern Hemisphere 
where under varied bathymetrical conditions the Oligochaetan fauna has 
been well investigated by many of the foremost workers on the group,, 
have not revealed any Phreodrilid representatives — and the same applies- 
in the case of the tropics — may very reasonably be interpreted as- 
indicating the restriction of the family to the area including the various 
parts where they are now known to occur. 
In a previous paper it was noted by one of us that the habitat appealed 
in its peculiar conditions as a significant fact. 
All the Phreodrilidae yet discovered and described are inhabitants of 
cold areas, with the exception of Astacopsidrilus which, however, can be 
neglected here since its peculiar external appearance bound up with its. 
unique association with the Crayfish — Astacopsis — makes it appear as 
being sui generis, and explains its bathymetrical and exceptional 
distribution. The various forms, if not inhabiting areas with a constant 
low temperature as in the Falkland Islands, occur on mountains exceeding 
easily 3,000 feet, and we now know that the worms appear in the pools 
only -during the colder seasons of the year. 
