BY E. J. GODDARD. 73 



that genus, and is to be found in Victoria and Tasmania, and in 

 New Soutli Wales. Geobdella is represented by three species — 

 G. aiisiraltensis, G. Whitmani, and G. tristriata — the former two 

 being present in New South Wales and Queensland, and the 

 latter in New Guinea. This latter distribution is of interest 

 from a zoogeographical standpoint. The fact that they are so 

 <;onfined in their distribution would seem to indicate with some 

 certainty that the problem of migration of the species of these 

 terrestrial forms is much more difficult than in the case of the 

 aquatic forms, and that we may consider them, in their distri- 

 Ijution, seriously in connection with zoogeographical schemes. 

 Again, these forms are in all probability limited to the eastern 

 side of the continent, the conditions of moisture, and the sub- 

 tropical nature of a good part of this area being much more 

 suitable for such forms of life. We may probably conclude from 

 this that the genus Geobdella had a range extending from 

 Austz'alia through at least part of the once existing Austro- 

 Malayan Peninsula, and that in all possibility sufficient time has 

 elapsed since the separation of this land-mass from Australia to 

 allow of the evolution of the New Guinea species, G. tristriata, 

 which is quite distinct from the Australian forms, and like them 

 is terrestrial. Further, we are also to regard Philcemon as being 

 characteristic of the southern half of the old Australasian conti- 

 nent, including Tasmania, and Geobdella of the northern and 

 more tropical half. 



Perhaps I ma}' he excused, preliminarily, before entering on a 

 discussion of the affinities of these two genera, if I attempt 

 to review in consideration the distribution of these forms with a 

 view to demonstrating their antiquity. If we assume that the 

 occurrence of one and the same species of P/ii/«;»jo/i in Tasmania, 

 Victoria, and New South Wales, is not due to the interference of 

 mankind (and this assumption I strongly support later), then we 

 must conclude that this genus once spread over the whole 

 of these combined areas when a land-connection existed between 

 Victoria and Tasmania, and further that inasmuch as only one 

 species is known, the genus must be a distinctly archaic one. In 

 support of this, we have the intere.sting fact that Geobdella, 



