98 



This species is represented to me by a single well-preserved 

 specimen. Dr. Cox, having purchased a collection of land shells 

 from a digger returned from New Guinea, found it jammed in 

 the aperture of a large Rhysota hercules. 



It is the smallest known Placostylus, and is remarkable besides 

 for its narrow shape, blunt anterior extremity and peculiar 

 aperture. Indeed it has a better claim to subgeneric distinction 

 than have some proposed divisions of the genus. One of the 

 chief claims it has on our attention is the extension of the geo- 

 graphical range which it brings to the genus. 



In a paper read before this Society some years ago I pointed 

 to Placostylus as illustrative of the antiquity, separation from 

 outside and faunal unity within, of the larger islands of the 

 South-West Pacific, deducing that New Zealand was an ultimate 

 link thereof, that her fauna was thence derived, and " that this 

 Melanesian plateau was never connected with, nor populated 

 from Australia, probably its fauna was derived from Papua cia 

 New Britain."* 



I am now disposed to regard Placostylus as an extremely 

 ancient group of Antarctic origin, and consider that the present 

 species strayed northwestwards by a now broken land route 

 when Papuina, the land operculates and numerous other forms, 

 passed from New Guinea, through New Britain and New Ireland 

 into the Solomons. 



The first writer, so far as my reading has served me, to recog- 

 nise the geological connection between New Caledonia and New 

 Zealand, was Heurteau.f He quotes the Rev. W. B. Clarke as 

 also supporting the idea, but I have not been able to find in the 

 writings of the latter author any statement to this effect. 



The whole subject has been recently and thoroughly reviewed 

 by Crosse. I 



A broken shell of an undetermined Placostylus in tne British 

 Museum is said, on the authority of Daintree, to have been found 



* P.L.S.N.S.W. (2), vii. p. ,339; reprinted Annals & Mag. Nat. Hist. 

 No. Ixvi. June, 1893, pp. 435-438; see also Thomson, Proc. Roy. Geogr. iSoc. 

 Australasia (Queensland), Vol. viii. pp. 17-24, and ix. p. 23. 



+ Rapport sur la Constitution de la Nouvelle Caledonie, 1876, p. 17. 

 X Journal de Conchyliologie, xlii. 1894, pp. 443-456. 



