HELIX-GERONTIA. 65 



a species of Patula, Suter has changed the family name to Phenaco- 

 helicidce, 'including therein the genera Phacussa Hutt., Thalassia 

 (Hutt. non Alb.), Gerontia Hutt., Pyra (Hutt. non Stal.), Pyrrha, 

 Therasia, Phenacohelix, Patulopsis (Suter non Strebel), Amphidoxa 

 (of N. Z. authors, non Alb.) and Calymna. Now with the excep- 

 tion of Phacussa and perhaps Thalassia, these groups have a denti- 

 tion unequivocally Patuloid. The figures given by Hutton and by 

 Suter do not satisfactorily show the contours of the basal plates 

 (base of attachment) of the marginal teeth of Phacussa or Thalas- 

 sia, and I can therefore offer no intelligent opinion upon the sys- 

 tematic position of those groups ; but I am inclined to regard the 

 marginal teeth as pseudo-zouitoid, rather than truly aculeate. 



The names proposed for species of this group in chronological 

 order are as follows : 



1. Gerontia Hutt., Trans. N. Z. Inst. xv, p. 135, May, 1883. 

 (Type G. pantherina Hutt.) 



2. Therasia Hutt., Ibid, xvi, p. 182, May, 1884. (Type T. cel- 

 inde Gray.) 



3. Calymna Hutt, Ibid, xvi, p. 199, May, 1884. (Type C. costu- 

 lata Hutt.) 



4. Pyrrha Hutt., Ibid, xvi, p. 200, May, 1884. (Type P. cressida 

 Hutt.) 



5. Psyra Hutt., Ibid, xvi, p. 201, May, 1884, (Type H. dimorpha 

 Pfr.) 



6. Phenacohelix Suter, Ibid, xxiv, p. 270, 1891. (Type H.pilula 

 Eve.) 



7. Patulopsis Suter, Ibid, xxiv, p. 270, 1891. (Type H. ide 

 Gray.) 



For further notes, see The Nautilus for September, 1892, p. 54. 



Section GERONTIA Hutton (s. ( str.). 



G. PANTHERINA HllttOIl. Vol. IX, PI. 3, figS. 1, 2, 3. 



Shell depressed, broadly and deeply umbilicated, obtusely cari- 

 nated above the periphery ; thin and rather fragile ; green-corneous, 

 a little translucent. Surface lustrous, sculptured with close fine, 

 unequal ribs of cuticle. 



Spire slightly convex ; whorls 4, convex, separated by deep 

 sutures, the last whorl not descending in front. Aperture oblique, 

 round-lunar ; peristome thin and simple ; parietal wall smooth, 

 blue-white. Alt. 4?, diam. 9 mill. 



5 Greymouth, New Zealand. 



