66 ON THE VICTORIAN LAND PLANARIANS. 



7. G. m'mahoni, n. sp. 



8. G. alba, u. sp. 



9. G. hoggii, n. sp. 



10. G. sugdeni, n. sp. 



11. G. mediolineata, n. sp. 



12. G, qnadrangiUata, n. sp. 



13. G. walhallcB, n. sp. 



14. G. fletcheri, n. sp. 



16. Rhynchodemus victorice, n. sp. 



Of these fifteen species the first three occur also in New South Wales and have 

 been already described by Moseley and Fletcher and Hamilton. The twelve 

 remaining species are, so far as is yet known, exclusively Victorian, but it is more 

 than probable that some of them will sooner or later be discovered in one or other 

 of the adjacent colonies. Still it is evident, when we consider that out of twenty- 

 nine known Australian species, nearly equally divided between the colonies of 

 Victoria and New South Wales, only three have been found in both colonies, that 

 the land Planarians, however widely they may be distributed as a class, do not enjoy 

 wide specific areas of distribution ; or, in other words, that in different districts of 

 the same country we may expect to find different species of Planarians. In spite of 

 the occurrence of one or two comparatively widely ranging species, such as Geoplana 

 alba, which I have had from M'Mahon's Creek, Warragul, Macedon, and Croajin- 

 golong, this expectation is justified by my own observations. 



With regard to the question of specific distinctions I have come to the conclusion 

 that we may safely rely on a combination of the following characters (1) the colour 

 and pattern, (2) the position of the external apertures, (3) the general shape of the 

 body. Although I have examined considerable numbers of the same species, as, for 

 example, in the case of Geoplana spenceri and G. hoggii, I have not found any 

 important variations in these respects. Perhaps the most variable species are the 

 common yellow Planarians which I have named Geoplana sugdeni and G. mediolineata. 

 These two species agree fairly well in the general shape of the body and in the 

 position of the external apertures, but the former has none of the stripes present in 

 the latter. The two species are, however, connected by an intermediate variety with 

 imperfect stripes. Under these circumstances I have assigned all specimens with 

 any stripes at all to G. mediolineata and all those without any to G. sugdeni. It 

 must, however, be remembered that although in G. mediolineata the number of 

 stripes may vary yet the arrangement is always identical, and this is the important 

 point. In the most perfectly striped examples which I have seen we find a single, 

 fine, dark median stripe, a lighter stripe at some distance on each side of it, and 

 outside this again on each side an indication of a stripe at the anterior extremity of 



