172 Transactions. — Zoology. 



Dentition, 18-1-18. Laterals 7. 



Central tooth rectangular, as broad as long ; the reflexed portion 

 tricuspid, the middle cusp reaching a half and the side-cusps a third of 

 the length of the base. Inner laterals rather longer than broad, tricuspid, 

 the reflexed portion constricted at the sides, the middle cusp reaching 

 almost to the posterior margin, and with a small point : outer laterals 

 with the inner side of the reflexed portion hollowed out ; the outer side 

 with a small constricted cusp, middle cusp with a large point. Inner 

 marginals tridentate, the inner and middle points larger ; outer marginals 

 much broader than long, with a single dentate point, which gets smaller 

 outwards and disappears altogether on the two last. 

 Hab. Greymouth (E. Helms). 

 Paryphanta jeffreysiana, Pfeiffer. PL xi., fig. f. 

 Jaw, none. Dentition, 9-0-9. 



Transverse rows of teeth forming an obtuse angle. Teeth robust, all 

 aculeate, smooth, the points rounded ; increasing in size from the first to 

 the fifth and then decreasing. The first about equal to the ninth ; the 

 third equal to the eighth. 



Hab. Auckland (T. F. Cheeseman). 

 Paryphanta coresia, Gray. PI. xi., fig. e. 

 Jaw, none. Dentition, 9-0-9. 



Transverse rows of teeth forming an obtuse angle. Teeth rather robust, 

 all aculeate, smooth, the points rounded ; increasing in size from the first 

 to the fourth and then decreasing. The third as large as the fifth. 

 Hab. Auckland (Cheeseman). 

 The teeth are more slender than in jeffreysiana. 

 Nanina marine, Gray. PI. ix., fig. r. 



Jaw arcuate, not tapering, papillate, with about 33 flat ribs. 

 Dentition, 47-1-47, without distinction between laterals and marginals. 

 Central tooth rectangular, the length three and a half times the breadth ; 

 the reflexed portion less than half the base, constricted at the sides and with 

 a moderate point. Laterals larger than the central tooth ; the reflexed 

 portion minute, not more than a quarter of the base, bicuspid, the inner 

 cusp with a long, the outer with a small point. Towards the margin the 

 teeth get smaller and the points nearly equal. The two outer are minute 

 and without points. 



Hab. Auckland (T. F. Cheeseman). 

 Phacussa helmsi, Hutton. PL x., fig. i, and pi. xi., fig. w. 

 Jaw arcuate, not tapering, with 20 or 25 flat ribs which indent the con- 

 cave margin. 



Dentition, 28-1-28 ; varying from 26 to 30. Laterals 11 or 12. 



