460 GASTROPODA. [Pectinibranchia. 



KEY TO SPECIES. 



A. Height of shell 6 mm. or less ; colour white, rarely with 2 yellow 



spiral bands ; outer lip smooth inside . . . . . . albescens. 



B. Height of shell 8 mm. or more ; body-whorl with a median brown 



band, or the shell may be quite white ; outer lip smooth or 



slightly crenate inside . . . . . . . . . . mustelina. 



4. Marginalia albescens, Button, 1873. Plate 20, fig. 12. 



Marginella albescens, Hutt., C.M.M., 19 ; M.N.Z.M., 62 ; Suter, T.N.Z.I., 

 xxxviii, 331. M. (Volvaria) infans, Reeve: Button, T.N.Z.I., xvi, 

 224 ; Index, 74, not of Reeve. 



Shell small, cylindrical, thin and fragile, translucent, polished, 

 smooth, white. The only sculpture consists of microscopic straight and 

 fine growth-lines. Colour white, rarely with indications of 2 yellow 

 spiral bands, sometimes with a faint median white band on the body- 

 whorl. Spire low, conoidal. Protoconch small, flatly convex. Whorls 



3 to 4, the last occupying nearly the whole height of the shell, rightly 

 convex. Suture indistinct. Aperture high and narrow, lightly chan- 

 nelled above, roundly truncated below. Outer lip vertical, straight, 

 retrocurrent towards the suture, with a faint indication of an outer 

 varix, thickened and smooth within. Columella a little oblique, with 



4 oblique and equidistant sharp plaits. The inner lip very thin and 

 transparent. 



Diameter, 2-5 mm. ; height, 5 mm. (type). Diameter, 1-8 mm. ; 

 height. 3-8 mm. (Foveaux ' Strait. 15 fathoms). Diameter, 3 mm. ; 

 height, 6-1 mm. (Cuvier Island, 38 fathoms). 



Animal unknown. 



Type in the Dominion Museum. Wellington. 



Hob. Stewart Island (type) ; Foveaux Strait, in 15 fathoms ; 

 Cuvier Island, in 38 fathoms ; Chatham Islands ; near the Snares and 

 Bounty Islands, in 50 fathoms (Captain Bollons). 



Remark. A very variable shell with regard to size. I have not 

 seen any specimens with indications of 2 yellow spiral bands. 



Fossil in the Miocene. 



5. Marginella mustelina, Angas, 1871. Plate 20, fig. 13. 



Hyali-na (Volvarina) mustelina, Ang., P.Z.S., 1871, 14, pi. 1, f. 5. Mar- 

 ginella mustelina, Angas : Hedley, Mem. A.M., iv, 1903, 366 ; Index, 

 74; Man. Conch. (1), v, 48, pi. 12, f. 87. M. Stanislas, T. -Woods, 

 P.R.S. Tas., 1876 (1877), 133; Tate and May, P.L.S. N.S.W., xxvi, 

 362, pi. 26, f. 82. 



Shell moderately large, cylindrical, thin, translucent, with a broad 

 spiral brown band on the middle. There is no sculpture whatever, the 

 whole shell being smooth and polished. Colour yellowish -white ; 

 suture with a narrow brown band, which may widen upon the body- 

 whorl, but usually a second narrow band is present, and this is sepa- 

 rated by a narrow white band from the median dark-brown spiral 

 band ; base with a narrow brown band ; the narrow brown bands 

 above ami below are sometimes dissolved into spots. Spire very low, 



