494 THE LAND AND FRESH- WATER MOLLUSCA OF NEW ZEALAND, 



beyond the base. The intermediate teeth show a stronger devel- 

 opment of the inner side and median cutting point, the reflection 

 is getting broader and longer, and in the marginal teeth we find 

 a broad, more or less quadrangular reflection with three or four 

 cutting points, the two inner ones much longer than the others. 

 The last but one is bidentate, the last minute, without cutting 

 point. The other radula I described had the formula 15 — 1 — 15. 



Ptychodon hunnaensis, n.sp. 

 (PL xxiiL figs. 8-8c.) 



Shell minute, sub-discoidal, umbilicated, pale horny, with 

 distant irregular broad streaks of rufous ; not shining, thin and 

 fragile, semi-transparent. Whorls 5, narrow, regularly increasing, 

 slightly rounded, the last proceeding considerably below the 

 penultimate; with radiate, fine, nearly straight ribs, about 15 per 

 millm., slightly directed forwards. Spire short, almost flat. 

 Apex blunt, smooth. Suture impressed ; periphery rounded. 

 Aperture rotundly-lucar, oblique, excavated by the penultimate 

 whorl in the upper part. Peristome straight, acute, margins 

 convergent, regularly arched, columellar margin descending 

 obliquely, not reflexed. Aperture with 12 teeth, three on the 

 penultimate whorl, two on the columella, and seven on the 

 parietal wall. On the penultimate whorl is centrally situated a 

 stout lamina, forked at the top by a broad groove, and below it 

 are two acute laminae at regular intervals of one-third. From the 

 columella two large blunt teeth, on a common base, extend rather 

 far into the aperture. The parietal wall is covered with seven 

 somewhat irregular and rather blunt teeth. Umbilicus broad, 

 perspective, occupying nearly one-third of the diameter. Base 

 rounded. 



Diam., 2 ; height 1 millm. 



Ilah.—^OYth Island : Hunna Range (Capt. T. Broun), Taupiri 

 Mt. (A. T. Urquhart), Waimarama, Hawke's Bay (A. Hamilton). 



A single specimen only from each locality. 



