![Thumbnail: [Volume 24, 1891 page 270]](/journals/rsnz/images/rsnz_24/thumbnails/rsnz_24_00_0331_0270_ac_02.gif)
[Read before the Philosophical Institute of Canterbury, 4th November, 1891.]
Professor F. W. Hutton, in his “Revision of the Land Mollusca of New Zealand” (Trans. N.Z. Inst., vol. xvi.), after having examined the dentition of a large number of our molluscs, was the first to see the necessity of establishing a family for those of our land-shells which represent intermediate forms between the Limacidæ and Patulidæ. This family he called Charopidæ (Trans. N.Z. Inst., vol. xvi., p. 199), including in it the genera Gerontia, Pyrrha, Charopa (Ch. ida), Psyra, Therasia, and Thalassia. Now, the type of the group or genus Charopa, Albers, is our Patula coma, Gray (Albers, Die Heliceen, II. Ausgabe, von E. von Martens, p. 87); and I think we should retain the name of Charopa for the group of P. coma, Gray, which belongs to the family of the Patulidæ, We therefore have to look for another name for our shells. None of the groups established by Albers or Pfeiffer can be taken into consideration. We have to deal here with evidently very old forms, showing peculiarities in their animals which hardly are met with in the Northern Hemisphere. The flora and fauna of New Zealand are well known for their peculiarities, and our land and fresh-water molluscs form no exception to the rule. How far similar forms are distributed over the Southern Hemisphere remains to be investigated. In my collection I used for several years the name of Pseudohelicidæ for this family; but I have to give it up, as Dr. O. Boettger in 1890 gave the name of Pseudohelix to a group of Vertigo, and I propose now the name of Phenacohelicidæ.
The genus Phenacohelix I substituted for Fruticicola (Trans. N.Z. Inst., vol. xvi., p. 194), as Professor F. W. Hutton fully agrees with me that none of our New Zealand shells belongs to Fruticicola. It includes Ph. pilula, Reeve; Ph. granum, Pf.; and Ph. chordata, Pf.
The generic name of Charopa, given by Professor F. W. Hutton to Helix ida, Gray, I propose to change to Patulopsis.
The family of the Phenacohelicidæ contains molluscs which are characterized by the heliciform animal possessing a caudal gland; the jaw is, with few exceptions, ribbed, stegognath; the marginal teeth show all intermediate forms from aculeate to quadrate, but even in the latter case some of the cuttingpoints are usually very long. The shell is that of Helix, spire
![Thumbnail: [Volume 24, 1891 page 271]](/journals/rsnz/images/rsnz_24/thumbnails/rsnz_24_00_0332_0271_ac_02.gif)
flat or elevated, umbilicated or imperforate; peristome acute; aperture without lamellæ; epidermis smooth or ribbed, seldom hairy.
The genera I include in the family of the Phenacohelicidæ are the following: Phacussa, Thalassia, Gerontia, Psyra, Pyrrha, Therasia, Phenacohelix, Patulopsis, Amphidoxa, and Calymna. They are in such a succession that Phacussa stands nearest to the Limacidæ, and Amphidoxa, with Calymna, nearest to the Patulidæ.
On examining the dentition of Diplomphalus subantialba, mihi, and D. biconcava, Pf., I have satisfied myself that I was mistaken when I placed several of our shells in this genus (Trans. N.Z. Inst., vol. xxii., p. 226), as there is a jaw, and consequently the radula is quite different from that of Diplomphalus.
With regard to the genus Hyalina I am more doubtful than ever. The species H. microreticulata, mihi, and H. allochroida, mihi (Trans. N.Z. Inst., vol. xxii., p. 227, 228), very likely belong to another genus; but as long as I have not had an opportunity of examining the animal I must defer settling the question.
The examination of the dentition of Endodonta leimonias, E. pæcilosticta, and E. marina decidedly shows that these shells must be included in Phrixgnathus, Hutt., and do not belong to Endodonta. The group Laoma was established by Gray in 1849 for Bul. leimonias, and I propose to retain it for the shells mentioned, as a subgenus of Phrixgnathus. This subgenus includes those species of Phrixgnathus which are provided with spiral laminæ and teeth in the aperture.
I wish to give complete lists of the land and fresh-water molluscs I found in two different places of this colony, at each of which I have been collecting occasionally during about one year and a half.