238 GASTROPODA. [Pectinibranchia. 



1. Cerithidea alternate, Hutton, 1873. Plate 39, fig. 12. 



Cerithium alternatum, Hutt., C.M.M., 26. Cerithidea alternata, Hutt , 

 M.N.Z.M., 74. 



Shell moderately large, turriculated, rather solid, costate, and 

 spirally grooved. Sculpture consisting of distant broad and rounded 

 axial ribs, 8 to 9 on the last whorl, cut up into broad and narrow 

 nodules by the spiral grooves, which are deep and having a small 

 ridge in the bottom of each ; there are about 10 of these grooves 

 on the last whorl, 2 on the periphery of the base having 2 small ridges. 

 Colour yellowish-brown. Spire elevated conical, twice the height of 

 the aperture ; outlines straight. Protoconch eroded. Whorls about 1 1 , 

 regularly and rather slowly increasing, slightly rounded ; base flat, 

 oblique. Suture impressed, margined above, wavy below. Aperture 

 oblique, ovate, channelled above, produced at the base into a very 

 short oblique and truncated canal. Interior white. Outer lip convex, 

 thickened but sharp, denticulated outside by the spiral sculpture, 

 grooved inside, each groove corresponding with an outer spiral riblet. 

 Columella vertical, excavated, truncated below. Inner lip sharply 

 limited outside the columella, united with the outer lip over the 

 parietal wall. Operculum unknown. 



Diameter, 10 mm. ; height, 24-5 mm. (type). Angle of spire, 23. 



Animal unknown. 



Type in the Dominion Museum, Wellington. 



Hob. Tauranga (type). 



2. Cerithidea bicarinata, Gray, 1843. Plate 39, fig. 13. 



Cerithium bicarinata, Gray, Diefi. N.Z., 241. Cerithidea (Pirenella) bicari- 

 nata, A. Adams, P.Z.S., 1854, 83. Cerithium bicarinatum, Gray : 

 Sowerby, Thes. Conch., ii, 288. Cerithidea bicarinata. Gray, Conch. 

 Icon., xv, f. 27 ; Ereb. & Ter., pi. 1. f. 20 ; Man. Conch. (1), ix, 1(33, 

 pi. 35, f. 15. Cerithium hitulentum, Kiener, Coq. Viv., 63, pi. 22, f. 3. 



Shell turreted, moderately solid, costellate. Sculpture consisting 

 of rather distant axial plications, 12-15 on the penultimate whorl, 

 slightly arcuate, prominent or subobsolete, crossed by numerous 

 spiral cords, mostly visible only on the lower whorls ; base with a 

 double ridge on its periphery, the lower one much stronger and sepa- 

 rated by a groove from the upper ridge ; the latter margins the suture 

 of the last whorl ; the lower ridge enters the aperture, forming with 

 the outer lip a parietal channel ; base with distinct growth -lines. 

 Colour blackish-purple or brown, often with a brown or whitish coat- 

 ing. Spire very high, conic, about three times the height of the 

 aperture ; outlines straight. Protoconch eroded. Whorls about 12, 

 regularly increasing, convex ; base concave. Suture impressed. Aper- 

 ture ovate, produced into a very short, open, oblique, and truncated 

 canal. Interior blackish-brown. Outer Up convex, straightened above, 

 very little thickened and expanded, sharp, with an interior orange 

 margin. Columella light brown, slightly concave, smooth, base ob- 

 liquely truncate. Operculum normal. 



