THE NAUTILUS. 123 
was a young Gundlachia! In his list of Tasmanian mollusca, 1890, 
he simply drops his A. woodsi without mentioning that it is a 
young Gundlachia. I have not yet found full-grown specimens of 
our Gundlachia, but I hope to succeed later on, and it is to be ex- 
‘pected to be a similar form to G. petterdi Johnston. 
Prof. Hutton suggested to me that this Gundlachia might, per- 
haps, have been introduced from Tasmania on aquatic plants, which 
were used in packing trout ova, and as our fish-hatching ponds are 
in communication with the river Avon, there is all possibility of 
this being really the case. However, there is one objection. Up to 
the present day I found our Gundlachia only on aquatic plants in 
the lower parts of the river, from the outflow of Horseshoe Lake to 
New Brighton, but not upward between this outflow and the fish- 
hatching ponds. This makes it very likely that Gundlachia occurs 
in the swampy Horseshoe Lake, difficult of access, and was washed 
down in the river Avon when the canal was cleared from Anacharis 
weeds. If this mollusk is really indigenous, it will, no doubt, be 
found in jocalities where the introduction from Tasmania is out of 
question, but as long as this is not the case, we must remain doubt- 
ful on this point. 
In the “ Reference List” I published with my friend Mr. Ch. 
Hedley, of Sydney (Proc. Linn. Soc. N.S. W., vol. VII (2) p. 624), 
he put down Ancylus tasmanicus Tenison-W oods, as being synonymous 
with A. woodsi. _ This is wrong, as the former is quite different, and 
I believe it to be really an Ancylus. A. australicus Tate and A. 
smithi Cox are very likely also young forms of Gundlachia. <A. 
assimilis Pett. and A. oblonga Pett. I have notseen. It would be of 
highest interest to examine the dentition of the Caledonian A. reti- 
culatus Gassies and A. noumeensis Crosse, which Mr. Hedley thinks 
to be nearly allied to the so-called A. woodsi. 
2. Rhytida meesoni Suter (Reference List, |. c. page 631) is no 
Rhytida, but a Paryphanta, as the animal lays calcareous eggs, 
whilst the genus Rhytida is considered to be viviparous. The genera 
Paryphanta and Rhytida are in the shells, the exterior of the ani- 
mals and the radula so nearly allied, that it is not always easy to 
separate them. Very likely the genital organs will show generic 
differences, and it is my intention to study the anatomy of these 
genera as soon as opportunity offers and time permits. 
3. Thalassohelix ziczae Gould. There was always some doubt 
whether this shell was really a New Zealand species or not, and at 
