246 THE PROCEEDINGS OF THE LINNEAN SOCIETY 



Shell depressedly conical, suborbicular, imperforate, rugoso- 

 plicate, subplicate, or nearly smooth, pale yellow, whitish or brown, 

 clouded, striped with pale green, sometimes mottled white, aud 

 livid on the upper whorls ; very distinctly spirally grooved, and 

 crossed with much inclined diagonal lines of growth ; whorls 6-7 

 generally undulately plicate at the suture, which is either 

 impressed or overlapping ; base very flat, acutely angled at the 

 periphery, which is undulating or round, according as the whorls 

 are plicate or not, spirally Urate with 5-7 spirally raised lines which 

 are diagonally crossed with strongly mai'ked lines of growth and 

 very finely, almost squamosely undulately striate ; periphery mar- 

 gined at the base ; that is to say, there is always a clear marginal 

 space between the lira? and the edge ; aperture subquadrate, much 

 produced above ; throat conspicuously enamelled ; outer lip thin, 

 margined within with a yellow line, and then generally a rich deep 

 brown ; base of throat wholly white, or with a broad white band ; 

 columella conspicuously orange, and spirally grooved posteriorly 

 (visible under the lens) ; the upper part of the throat sometimes 

 brown, sometimes white, but always enamelled. Dimensions of 

 the largest specimen : diameter of base 17, alt. 14, of the smallest 

 ll-7i millimetres. 



It is worthy of remark that in this variety there is little or no 

 thickening of the base, which is denticulate at the edge, but not 

 lirate within ; and finally, that the deep brown color is a thick 

 vitreous translucent substance easily separated from the shelly 

 outer covering, and when the basal part of the throat is broken 

 away, it is seen to extend like a broad margin of brunswick black 

 round the upper interior. 



The operculum is a pale, translucent yellow, oblong, few whorled, 

 and an almost marginal nucleus. 



The odontophore (lingual ribbon) is a very fine, glassy, narrow, 

 flattened *mbe, about 20 millimetres long, and lying in a coil just 

 below the red fleshy buccal mass. Inside this tube the teeth are 

 affixed to a somewhat thickened transparent membrane. The 

 teeth are very numerous in sets or chevrons of seven ; that is 



