BY K. J GODDARD. 71 



Hiruflo. Limnohdella australis of Australia and L. mauiana of 

 New Zealand are exceedingly closely allied, and apparently they 

 differ onl}' in colour -pattern, and perhaps slightly in dimensions. 

 Their anatomy agrees in the points of difference as cited for the 

 differentiation of the genus from the common genus llirudo. 

 Whether we regard them as distinct species or not, their distri- 

 bution is of some interest. Tn support of this, we find in New 

 South Wales a new genus, Hirudobdella, which was originally 

 discovered by Prof. Benham in New Zealand, in the form Hirudo 

 antij)odum, which Prof. Benham himself thought must fall into 

 a new genus. Limnohdella is known from other parts of the 

 world, and so, like other freshwater forms, has a cosmopolitan 

 distribution. Hirudubdella, represented up to the present by 

 one New Zealand species and one Australian species, is also a 

 freshwater form; and, |)robably, when viewed critically from the 

 .standpoint of distribution, is to be regarded as a highly moditied 

 subgeneric offshoot from the Hirudo-stock. 



In considering the question of distribution, perhaps the most 

 important members of the Australasian Hirudinea are the 

 terrestrial genera, Philcemou and GeohdeUa. Before entering into 

 a discussion of the affinity and distribution of these forms, it 

 will perhaps not be out of place to point out the distribution of 

 the terrestrial ArhynchohdeUidce tliroughout the world, with a 

 view to pointing out the significance of their distribution in 

 bearing on zoogeogiaphical questions. 



The number of terrestrial species is very small: so far only 

 eight genera are known, five of which belong to the Gnathob- 

 dellidte and three to the Herpobdellidxe. The former include: — 



Htemadipsa Tennent, 1861; Ceylon, India, Burmah, and 

 Japan. 



Xerohdella von Frauenfeld, 1868; mountains of Europe. 

 Mesobdella Blanchard, 1893; Chili. 



Geobdella Whitman, 1886; Australia and New Guinea. 

 Philcemou Blanchard; Australia and Tasmania. 



