Tea vers. — Distribution of Paryphanta in N.Z. 225 



which was found by Sir James Hector near Waitapu, the boat- 

 harbour of the Takaka Valley in Massacre Bay. 



The distribution of these shells, so far as it is at present 

 known, is interesting. Busbyi appears to be coincident in 

 range with the kauri forest, for I am not aware that any 

 specimen has been found south of the parallel to the north of 

 which that timber is now growing. The typical hochstetteri, 

 of which the Waitapu specimen of Sir James Hector is an 

 example, was found, as already stated, on the mountain-range 

 between the valley of the Pelorus and that of the Maitai, 

 which flows into the Nelson Haven. I have already men- 

 tioned the localities in which the so-called dark hochstetteri 

 has been got, and it becomes an interesting point to determine 

 how this variety should have a place on both sides of Cook 

 Strait, and upon an island so isolated as Stephens Island, 

 and yet should never have been found within the area from 

 which the Picton shells have been obtained. I am not at 

 present in a position to solve the puzzle, but I have thought 

 that it might interest the members of the Society to hear 

 some of the known facts in regard to the distribution of land- 

 shells, in order, in the first place, that they may understand 

 the difficulty of solving puzzles of a similar nature, and, in 

 the next place, in the hope that it may stimulate observation 

 and inquiry in relation to our own particular instances. 



I need scarcely call your attention to the fact that 

 questions affecting the distribution and dispersal on the 

 face of our globe of all forms of life (using the words in their 

 widest sense) have acquired extraordinary importance amongst 

 naturalists since the publication of " The Origin of Species," 

 and that numberless theories have been propounded to account 

 for the anomalies often presented to us in connection with 

 this subject. One favourite theory, not yet entirely aban- 

 doned, has been founded upon supposed frequent and radical 

 changes in the distribution of land and water, but this theory 

 has gradually lost the support of those whose opportunities of 

 observation have been most extensive, and we are being taught 

 to look to the existence of other and yet of necessarily highly 

 effective means of dispersal, in order to account for the facts 

 which observation has brought under our notice. 



It has been shown, however, that in considering the 

 questions of distribution and dispersal no group of animals 

 presents greater puzzles than land -shells, for, as Darwin 

 pointed out, almost all oceanic islands, even the smallest and 

 most isolated, are inhabited by members of this group, gene- 

 rally endemic, though frequently mixed with species found 

 elsewhere; and yet it seems almost impossible to conceive 

 how (except where the agency of man can be referred to) 

 organisms which are very speedily killed by immersion in 

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