290 GASTROPODA. [Pectinibranchia. 



very slowly then rapidly increasing, the last very large, convex ; base 

 rounded. Suture well marked, not impressed. Aperture oval, sub- 

 vertical, interior light brown with a few lighter bands, white and 

 callous inside the margins. Outer lip convex, thin and sharp. Colu- 

 mella oblique, porcellanous, arcuate below. Inner Up forming a 

 strong semicircular white callus, entering the umbilicus, and sometimes 

 nearly filling it up, leaving only a channel and a narrow chink above, 

 spreading above as a thin white callosity over the parietal wall. Um- 

 bilicus with a distinct yellow callus spreading over part of the base. 

 Operculum semilunar, calcareous, paucispiral, nucleus near the lower 

 inner margin, inside with a yellowish horny and polished epidermis, 

 with radiate growth-lines and a few median spiral striae. 



Diameter, 21 mm. ; height, 24-75 mm. (type). Diameter, 26 mm. ; 

 height, 28 mm. (large specimen). Diameter, 19 mm. ; height, 22 mm. 

 (the usual size). 



Animal unknown. 



Type in the Mus. Hist. Nat., Paris. 



Hab. Throughout New Zealand and at the Chatham Islands ; 

 near Resolution Island, in 12 fathoms ; Stewart Island, in 18 fathoms ; 

 ofi Great Barrier Island, in 110 fathoms ; Hauraki Gulf, in 25 fathoms ; 

 Kermadec Islands. 



Fossil. Miocene and Pliocene. 



Genus 2. POLINICES, Montfort, 1810. 



Polinices, Montfort, Conch. Syst., ii, 1810, 223. Type : Nerita mammilla, L. 

 Natica, Risso, 1826 ; not of Lamarck, 1799. Albulci, Bolten, 1798 ; not 

 of Gronovius, 1763. Neverita, Risso, 1826. Euspira, Agassiz, 1842 (in 

 part). Lunatia, Gray, 1847. Cepatia, Gray, 1840. Velainia, Munier- 

 Chalmas, 1884. Naticina, Fischer, 1885 ; not of Guilding, 1834. 

 Sigaretopsis, Cossman, 1888. 



Shell oval-elongate, subglobular or depressed, generally smooth, 

 umbilicated or having the umbilicus closed by a callus. Operculum 

 corneous, paucispiral, semilunar, having the nucleus nearly lateral, 

 concave externally. 



Fossil in the Tertiary. 



1. Polinices amphialus, Watson, 1881. Plate 46, fig. 1. 



Natica amphiala, Wats., J.L.S., xv, 1881, 260; Chall. Rep., xv, 1886, 437, 

 pi. 27, f. 6. Natica vitrea, Button, C.M.M., 21. Lunatia vitrea, Butt., 



M!N.Z.M., 72. 



Shell thick, depressedly globose, with a small scalar rather elevated 

 spire and a narrow obliquely pointed base, pale yellow, umbilicated. 

 Sculpture : Longitudinals there are many fine close-set lines of 

 growth ; spirals there are a few faint traces of obsolete lines and 

 furrows, there is a slight angulation round the mouth of the umbilical 

 pore. Colour is slightly brownish-yellow, but is pure porcellanous- 

 white below the epidermis, which is thin, slightly puckered, smooth, 

 not glossy, persistent. Spire short, but abrupt and scalar. Proto- 



