president’s ADDRESS — SECTION D. 
117 
parts of the world, including Australia and New Zealand. The- last- 
named species, indeed, would seem to adopt this plan as an ordinary 
method of multiplication.* 
Only four genera of Land Planarians are known to occur in 
Australia— namely, Geoplana , which is by far the commonest, and 
which is characterised by the large number of minute eyes (absent, 
however, in G. ty phi ops) and the absence of differentiated head and 
anterior sucker ; li.hynchodemus, comparatively rare, and distinguished 
from Geoplana bv the presence of only a single pair of eyes ; Cotylo- 
pinna, lately described by Professor Spencer, from Lord Howe Island, 
and characterised by the presence of a single pair of eyes and an 
anterior ventral sucker ; and Bipalium , evidently introduced into 
these colonies by man, and at once recognisable by the characteristic 
cheesecutter-shaped head. 
Although the genera are thus easily distinguished from one 
another, the question of specific distinction is one of some little 
difficulty. Experience, has, however, shown beyond doubt that for 
practical purposes the colour and pattern, associated with the shape 
of the body and the position of the external apertures, afford very good 
guides in recognising the species. That the pattern may sometimes 
vary considerably within the species no one need deny,f but this 
variation has its limits, and can be checked by the other characters 
mentioned. How far the results arrived at by the study of these 
external characters will be borne out by investigations upon the 
internal anatomy remains to be seen ; and we may hope for much 
light on this question from Professor von Graff’s forthcoming Mono- 
graph. 
In the meantime it appears to me that we may not only dis- 
tinguish the species by the external characters mentioned, but that we 
may also group them together in natural subdivisions of the genera. 
Possibly in the future each of these subdivisions may take rank as one 
species with a number of varieties, but it appears to me more likely 
that each will have to rank as a distinct genus. These points can only 
be determined by a careful study of the comparative anatomy of the 
group. 
As regards the geographical distribution of the Australasian Land 
Planarians, we must wait for more extensive investigation before we 
can venture to draw any general conclusions. Meanwhile, the follow- 
ing facts may be pointed out: — The widely distributed genus Geoplana 
occurs in all the Australasian colonies where it has been sought for, 
with the curious exception of Lord Howe Island. Rhijncliodemus is 
much rarer; unknown in Tasmania, and with only two species in 
Victoria, it becomes more abundant in New South Wales, and extends 
to Queensland (where we have not sufficient data to judge whether it 
is rare or otherwise), while in Lord Howe Island it appears from the 
collection made by Mr. Whitelegge, and described by Professor 
Spencer, to be the dominant genus, associated with the allied but 
* Vide Fletcher, “ Remarks on an introduced species of Land Plan an an v Proc. 
Linn. Soc. N.S.W. [Ser. 2], vol. ii . , p. 244. Also Bergendal, “Studien liber Turbel- 
larien, i. ?> Stockholm, 1892 (Kongl. svenska vetenskaps-akadamiens Handlingar, 
Band 25, No. 4). 
f I have illustrated this variation in the case of Geoplana Fletchen — Proc. Royal 
Soc. Victoria for 1893, Plate X. 
