634 I.ASTROPODA. \_Pulmonata. 



The shell is like a thin Selenites with delicate close riblets. It is 

 more broadly umbilicated than in the other genera of this family. 

 Distribution . New Zealand. 



KEY TO SPECIES. 



A. Shell with coarse growth-striae, marbled and streaked with 



brown ; periphery convex . . . . . . . . Cordelia. 



B. Shell with oblique membranous radial riblets, colour green- 



corneous ; periphery obtusely angled above . . . . pantherina. 



1. Gerontia Cordelia, Hutton, 1883. Plate 25, figs. 8, 8a, Sb. 



Gerontia Cordelia, Hutt,, N.Z.J.S., i, 1883, 476 ; T.N.Z.I., xvi, 178, 200 ; 

 Pilsbry, Man. Conch. (2), viii, 66, pi. 22, f. 34-36 ; Hedley and Suter, 

 P.L.S. N.S.W. (2), vii, 637. Flmmnnlina (Gerontia) Cordelia, Hutt, : 

 Suter, J. de Conch., xli, 243. 



Shell subdiscoidal, widely umbilicated. striated, thin. Sculpture 

 consisting of rather crowded and coarse growth-strife, with traces of 

 fine microscopic spiral lines on the protoconch. Colour pale-horny, 

 marbled and streaked with reddish-brown. Epidermis thin, yellow, 

 shining. Spire convex, about half the height of the aperture. Proto- 

 conch of 1J whorls, with a small shallow perforation at the middle. 

 Whorls 44, slowly increasing, rounded, periphery convex. Suture 

 impressed. Aperture slightly oblique, subcircular. Peristome thin 

 and sharp. Outer Up lightly descending. Columella slightly oblique, 

 almost straight. Inner Up very little reflexed. Umbilicus broad, 

 conical, showing all the whorls, about one-quarter of the greatest 

 diameter. 



Diameter Maj., 8mm. ; min., 6-75 mm. : height. 4-5 mm. 



Animal unknown. 



Type in the Canterbury Museum, Christchurch. 



Hob. Titirangi. Auckland, type (T. F. Cheeseman) ; Bay of 

 Islands. 



Remarks. I place this species in Gerontia from the general appear- 

 ance of the shell, but I do not know the animal nor the dentition. 

 It differs from G. panther inn in being more convex, in the epidermis 

 not being plaited, in being more coarsely striated, in the right margin 

 descending, in the aperture being less oblique, and in its colours. 

 (Hutton.)" 



2. Gerontia pantherina, Hutton, 1883. Plate 25, figs. 9, 9a, 96. 



Gerontia pantherina, Hutt., T.N.Z.I., xv, 1882 (1883), 135 ; xvi, 200 : 



bry, Man. Conch. (2), viii, 65, ix, pi. 3, f. 1-3 : Hedley and Suter, P.L.S. 

 N.S.W. (2), vii, 637 ; Suter, J. de Conch., xli, 243. 



l subdiscoidal, broadly umbilicated, thin, pellucid, striated. 

 Sculpture consisting of close but irregular oblique radial riblets. which 

 are membranous on the upper surface, tine and hair-like on the base ; 

 there are about 8 to 10 per millimetre : the interstices with numerous 



