BY HENRY SUTER. 487 



Some time ago I found a great number of the so-called Anclyus 

 Woodsi, Johnst., in the River Avon, and this time alive. On 

 examining the radula and com})aring it with that of a Gundlachia 

 from Ohio, U.S.A., I found that our mollusc is also a Gundlachia. 

 This was fully confirmed by finding a number of shells in which 

 the septum hud begun to form or was already completely formed, 

 and I hope to find full-grown Gundlachia later on. Prof. F. W. 

 Button suggested to me that this Gundlachia might have been 

 introduced from Tasmania on aquatic plants used for packing 

 trout ova. This question can of course only be settled definitely 

 when Gundlachia is found in other localities, where the introduc- 

 tion is out of question. There is, however, one reason which 

 leads me to think that this Gundlachia is really a New Zealand 

 mollusc. I found the shells up to the present time only at the 

 end of the outflow of Horse-Shoe Lake in the River Avon, and 

 from this place further down for about a mile on the same bank 

 of the river. I have not found Gundlachia from the outflow of 

 the lake upivards to the fish-hatching establishment, which is 

 distant several miles. This makes it very probable that the 

 original habitat of our shell is the Horse-Shoe Lake, and that it 

 was brought down to the river when the canal from the lake was 

 cleared from aquatic plants (Anacharis). The lake is very difii- 

 cult of access, and that is why I have not explored it yet. It 

 seems to me that Gundlachia wants for its full development a 

 still water, and that in the river the animals, at least most of 

 them, continue living in an Ancylus-^\\Q\\ and dying without ever 

 having made an attempt to build the peculiar shell of Gundlachia. 

 Therefore we find here as well as in Tasmania rather large ancyli- 

 form shells of this Gundlachia, whilst the shells with a septum 

 are of much smaller size. In Tasmania A. Woodsi is said to be 

 plentiful and Gundlachia very rare in the same locality. 



Paryphanta Meesoni, Suter, sp. 



No. 52 of the Reference List. It is not so very long ago that 

 I ascertained the fact that this species lays calcareous eggs and 

 can therefore not belong to the genus Rhytida^ where I first 

 34 



