SuTEii.— 0« New Zealand Mollusca. 131 



it could not be Z. nitida, but the specimens correspond with 

 Pfeiffer's diagnosis of H. novarce, with the only difference that 

 some of Mussou's specimens have |-1 volutions more, and are 

 therefore larger than the examples collected by Hochstetter. 

 On examining the animal and dentition I saw that it is not a 

 Flajnimdina, as first supposed, but an Ariophanta, the only 

 species of this genus known to me to occur in New Zealand. 

 It may therefore be of interest to have the dentition described 

 and figured. 



Jaio (fig. 26) membranaceous, smooth, upper margin 

 arched, lower margin almost straight, with an indistinct 

 median projection, ends tapering, faintly longitudinally and 

 vertically striated. 



Badula (fig. 27) tongue-shaped, formula 42 — 1 — 42, of 

 which 10 to 12 are laterals ; transverse rows of teeth straight. 

 Cezitral tooth long and narrow, with one long reflection, and 

 a short, stout cutting-point, extending a little over the next 

 row of teeth. Laterals broader, unicuspid, with a broad, blunt 

 cutting-point of the same length as the central. A large 

 number of intermediate teeth follow ; they are oblique, with a 

 bicuspid reflectioQ, and one stout, oval cutting-point. Mar- 

 ginals sinuate, bicuspid. 



20. Otoconcha dimidiata, Pfeiffer, sp. 1854. Plate XVIII., 



fig. 28, and Plate XIX., fig. 29. 



Some time ago I found a single specimen of this curious 

 mollusc at Port Hills, Lyttelton, the radula of which differs 

 slightly from that described and figured by Professor Hutton 

 (Trans. N.Z. Inst., vol. xvi., pi. ix., fig. Y). The specimen was 

 rather a young one. 



Jaio (fig. 28). It has hitherto been said that the jaw of 

 Otoconcha is ribbed, and at first sight it would seem to be so. 

 I have, however, quite a different opinion. The outlines of 

 the jaw figured are decidedly those of an oxygnath jaw% which 

 supposition is supported by the distinct longitudinal striation, 

 which is very often seen in the jaw of the Limacidcs. The 

 most irregular denticulation of the cutting-margin points to 

 the fact that this jaw cannot be considered as ribbed, but as 

 channelled by the action of the exceedingly strong cutting- 

 points of the radula. 



I therefore describe the jaw of Otoconcha as cxygnath, 

 smooth, longitudinally striated, with a strong median pro- 

 jection inferiorly, irregularly channelled, the channels in- 

 creasing in depth towards the cutting-margin, which is deeply 

 and irregularly denticulated. Ends blunt. 



The jaws of old animals represent only a narrow ledge 

 with blunt denticulations on the inferior edge ; perfectly worn 

 out by the action of the teeth. 



