SuTEB. — On Neu' Zealand Molbisca. 283 



tioned by Gray in Dieffenbach's "New Zealand," is not in 

 any of our museums with New Zealand as locality, and has 

 not been found here by any collector since it was described 

 by Gray. We therefore may place it amongst our very 

 doubtful species, though its occurrence in New Zealand is not 

 impossible, and would correspond with the habitat of Therasia 

 Ophelia, Pf., which is said to have been found also near Cape 

 York, Queensland. 



Abt. XXII. — Miscellaneous Gomviunications on New Zealand 

 Land and Fresh-water Mollusca. 



By H. SuTEK. 



lEead before the Philosophical Institute of Canterbury, 4th November, 



1891.] 



1. Potamoiryrgus. In my last paper on our molluscs (Trans. 

 N.Z. Inst., vol. xxiii., p. 94) I recorded the fact of P. corolla, 

 Gould, being viviparous. I unfortunately forgot to mention 

 that Professor F. W. Hutton had already brought this pecu- 

 liarity to our knowledge in 1881 for the species P. cwmingiana, 

 Fischer, and P. antipodnm, Gray (Trans. N.Z. Inst., vol. xiv., 

 p. 144), and had also given figures of the embryonic shells. 

 The priority of the discovery therefore belongs to our distin- 

 guished couchologist Professor F. W. Hutton. There remains 

 only P. pujjoides, Hutt., to be examined on its mode of pro- 

 pagation. 



2. Laovia marina, Hutt., and L. nerissa, Hutt. Some 

 years ago, when collecting in the Forty-mile Bush, North 

 Island, I had the opportunity of examining a good number of 

 the above-named shells, and I then made the observation that 

 the lamella^ of the aperture of these shells show a great varia- 

 bility. I found specimens showing the three lamellns only 

 oiLaoma marina, others^mostly smaller ones — with the seven 

 lamellae of L. nerissa ; but I obtained also a good number of 

 shells which were, with regard to the number of lamellae, in- 

 termediate forms, showing more lamelli» than L. marina and 

 less than L. nerissa. I thus became convinced that the two 

 species are in reality but one; but it was not until some 

 months ago that I found time for fuller investigation. Through 

 the kindness of Mr. Charles T. Musson, of Sydney, who had 

 been collecting in the Province of Auckland, I obtained a 

 number of shells, and amongst them twenty-nine specimens 

 of L. marina and nerissa, collected at Mount Wellington, 

 Auckland. These I submitted to a close examination, the 

 result of which I wish to give here. 



