130 Transactions. — Zoology. 



ant that we should get acquainted with its dentition, and I 

 therefore give here the figures of the jaw and part of radula. 



The jaw is composed of twenty-five separate strongly- 

 papillate plaits. The radula has the formula 25 — 1 — 25 ; the 

 central tooth is minute, unicuspid, the laterals and marginals 

 bicuspid. For details in the dentition of this and the following 

 three species of PlirixgnatMis I refer to former publications 

 by Professor Hutton .and myself. 



16. Phrixgnathus pumilus, Hutton, sp. 1883. Plate XVIL, 

 figs. 20, 21. 



The jaiv of this species was not seen by Professor Hutton 

 when he examined the dentition. It is distinctly papillate, 

 the plaits are narrow towards the ends, very broad in the 

 middle ; but this may differ with the individual. 



The central and lateral teeth are just as figured by Pro- 

 fessor Hutton (Trans. N.Z. Inst., xvi., pi. ix., fig. Q). The 

 marginals, which are figured here, are similar to the laterals, 

 bicuspid, but shorter, quadrate. 



17. Phrixgnathus microreticulatus, Suter, sp. 1890. Plate 

 XVIL, figs. 22, 23. 



This species was described by the writer as Hyalina 

 microret., but on examining the jaw and radula I saw that it 

 belongs to Hutton's Phrixgnathus. 



The jaio is formed of about eighteen separate slightly- 

 papillate plaits ; the radula has the formula 27 — 1 — 27, the 

 rachidian tooth unicuspid, the laterals and marginals bicuspid, 

 the last exceptionally tricuspid. 



18. Phrixgnathus allochroidus, var. lateumbilicatuSj Suter, 

 sp. 1890. Plate XVIII., figs. 24, 25. 



This is another of my supposed Hyalines, which on 

 examining the dentition turned out to be a Phrixgnathus ; 

 jaio with about twenty-one separate papillate plaits ; formula 

 of radula 14 — 1 — 14 ; central tooth tricuspid, with a median 

 cutting-point, laterals and marginals bicuspid. 



19. Ariophanta* novarae, Pfeiffer, sp. 1862. Plate XVIIL, 

 figs. 26, 27. 



As mentioned in my list of the introduced land and fresh- 

 water mollusca of New Zealand (Trans. N.Z. Inst., vol. xxiv., 

 p. 280), I suspected Mr. Musson's Zonitoides nitida, Miiller, 

 from Lake St. John, Auckland, to be not this species, but 

 PfeilTer's Hyalina novara. At my request Mr. Musson kindly 

 sent me a number of shells and animals. I at once saw that 



* Ariophanta, Dea Moulins, 1829 {Nanina, Gray, 1834 ; not Risso, 1826). 



