288 Transactions. — Zoology. 



the reflection showing a tendency to become tricuspid ; the 

 cutting-point broad, blunt, and short. 



Marginals stout, first longer than broad, then broader, 

 tridentate, the median tooth the stoutest. In the outer 

 marginals the teeth are blunt, the last marginal minute, with 

 two rudimentary teeth only. 



For two specimens of this species I am indebted to Mr. 

 B. Bull, of St. Albans. They were collected by Mr. G. J. 

 Eoberts in March, 1884, and accompanied by the following 

 note: "From head of Staircase Creek, 5,300ft. above sea- 

 level, on Nerger Eange, in slush of snow, hundreds together." 

 One of the specimens was broken, but fortunately contained 

 the dried animal, which I used for preparing the jaw and 

 radula. I never had a greater surprise in conchological work 

 than when I examined the dentition of this mollusc. The 

 shell is as near that of a Hyalina as it can be, but jaw and 

 dentition are widely different, and they agree with those of 

 our Amphixoda. 



The shell, of which I give a drawing, corresponds well with 

 Pfeiffer's description, and it differs very much from Hyalina 

 cellaria, with wliich Professor F. W. Hutton thought it to be 

 identical. The dimensions of the specimen from Nerger 

 Eange are : Diameter, greatest 8mm., least 6|-mm. ; height, 

 3Jmm. ; aperture, height 2^mm., breadth 3^mm. 



Amphidoxa compressivoluta, Eeeve. From Forty-mile 

 Bush, North Island. Plate XX., figs. 8, 9. 



Jaio almost straight, membranaceous, with very fine and 

 narrow vertical striae, one end blunt, the other slightly taper- 

 ing ; a short median projection on the cutting-margin. 

 Considerable magnifying shows the latter to be finely 

 denticulated. 



Bachila tongue-shaped, consisting of about a hundred 

 almost straight transverse rows of teeth, 32 — 1 — 32. The 

 number of laterals may be taken at about six, but they are 

 very gradually going over in marginals. 



Central tooth nearly quadrate, reflection tricuspid, the 

 median cusp with its cutting-point reaching to the posterior 

 end of the base, side-cusps sinuated, with a short cutting- 

 point on each. 



Laterals resembling the central, but the median cusp is 

 stouter, and its cutting-point extends over the posterior end 

 of the base ; the inner side-cusp gets broader, its cutting- 

 point more developed, whilst the outer one remains narrowed, 

 and its cutting-point small. 



In the transition teeth the reflection becomes bicuspid, 

 the inner cusp is large, extending to the posterior end of the 

 base, its strong cutting-point is slightly directed towards the 



