108 GASTROPODA. [Aspidobranchia. 



base flat. Suture superficial, with a nodulous border below. Aper- 

 ture oblique, rhomboidal. Outer and basal lip a little convex, form- 

 ing a sharp angle where they meet. Columella oblique, slightly con- 

 cave, with an almost imperceptible fold above. False umbilicus small, 

 smooth, almost filled up. Angle of spire, 70. 



Diameter, 9 inm. ; height, 7-5 mm. (type). Diameter, 11 mm. ;. 

 height, 8 mm. (Auckland Island specimen). 



Type in the Dominion Museum, Wellington. 



Hob. Chatham Islands (type) ; Foveaux Strait, in 15 fathoms ; 

 Wet Jacket Arm, near Resolution Island, in 12 fathoms (Captain 

 Bollons) ; Snares, in 50 fathoms (Captain Bollons) ; Bounty Islands, 

 in 50 fathoms (Captain Bollons) ; Auckland Islands (Captain Bollons). 



Remark. - - The specimens from deep water have no longitudinal 

 colour-markings. 



Fossil in the Pliocene. 



Subsp. dunedinensis, Suter, 1897. 



Trochus oppressus, Hutt., var. dunedinensis, Suter, P. Mai. S., ii, 261. 



Distinguished from the species by the lowest cord of the spire- 

 whorls being much less prominent, the last whorl in consequence 

 having no keel, but an angularly rounded periphery. The radiate 

 broad ribs are either absent or reduced to nodules below the suture. 

 The colour is greenish-brown, with indistinct oblique and olive-black 

 stripes. Angle, of spire, 70. 



Diameter, 7-5 mm. ; height, 7-5 mm. (type). 



Type in my collection. 



Hob. Dunedin Harbour, under stones (H. S.). 



Remarks. On re-examining my specimens I found them to stand 

 much nearer to T. chathamensis than to T. oppressus. The absence of 

 the strong keel on the body-whorl gives it at first sight a closer re- 

 semblance to the latter species, though there is no upper angle on the 

 body-whorl. 



2. Trochus oppressus, Hutton, 1878. Plate 38, figs. 2, 2a. 



Gibbula oppressa, Hutt., J. tie Conch., xxvi, 1878, 34; Man. Conch. (1), xi, 

 232, pi. 40, f. 4, 5. Trochvs oppressus, Suter, P. Mai. S., ii, 261. 



Shell small, conical, somewhat solid, lustreless, with a false um- 

 bilicus. Sculpture : The entire surface closely finely spirally striate, 

 the strise of the base becoming coarser toward the axis. Colour dark 

 olive-brown or greenish, minutely tessellated all over with a slightly 

 darker shade of the same hue. Spire conical. Protoconch conical, 

 small, 2 slightly spirally striated whorls. Whorls 5, those of the spire 

 keeled above the middle, body-whorl biangular ; base rather flattened. 

 Suture slightly impressed. Aperture oblique, subquadrangular, irides- 

 cent and slightly lirate within. Peristome sharp, discontinuous. Outer 

 and basal lip convex, with a narrow opaque margin within, which is 



