486 THE LAND AND FKESH-WATEll MOLLUSCA OF NEW ZEALAND, 



the upper margin meets the whorl. Base rounded, the mem- 

 branaceous plaits extending to the umbilical region, which is 

 slightly deepened. Umbilicus covered. 



Operculum lost in all the specimens I have seen. 



Diam. \\; height l|millm. 



Hah. — North Island : Hosvick and Hunna Range (Capt. T. 

 Broun). 



This species, like all the others of the genus, seems to be very 

 rare, but is, from its minuteness and dark colour, easily overlooked. 



GUNDLACIIIA sp. 



In the "Reference List," p. 624-, No. 24, it is mentioned that 

 specimens of Anci/lus tasmanicus, Tenison-Woods, were discovered 

 by me in New Zealand. I wish to point out that I never identi- 

 fied the Ancylus 1 found in the River Avon as A. tasmanicus, but 

 as A. Woodsi, Johnston (vide Journ. de Conch. Vol. xxxii. p. 250). 

 My friend Mr. C. Hedley substituted the former name as a 

 synonym for the latter ; but this, I think, is a mistake. There 

 can be no doubt whatever that the Tasmanian Ancylus Woodsi, 

 Johnst., is the young form of Gundlacliia Petterdi, Johnst. 

 Johnston himself says in his description of A. Woodsi (Proc. Roy. 

 Soc. Tasm. 1878, p. 25) : "Animal and teeth almost similar to 

 Gundlachia Fetterdi.^^ And in the description of the latter shell 

 (I.e. p. 23) he writes : '-In the young state the shell is simple and 

 resembles the Qovixmow Ancylus.'" This explains why Johnston in 

 his List of Tasmanian MoUusca (1890) does not mention his .4. 

 Woodsi, but unfortunately he also omits to say that it is synony- 

 mous with Gundlachia. A. Woodsi and Gundlachia are found in 

 the same localities, a fact which was stated to me by Messrs. 

 Beddome and May. " I think that Ancylus australicus, Tate, and 

 perhaps A. Sniithi, Cox, may also be young forms of Gundlachia, 

 and it is therefore desirable that their dentition should be 

 examined. I have not seen Ancylus assimilis, Pett., and oblonga, 

 Pett., but A. tasmanictis, Tenison-Woods, I take to be a true 

 Ancylus, and not a young Gundlachia. 



