326 trochid^:. 



ridge ; they closely resemble the tentacles in every particular, 

 except in being more slender ; each has a brownish eye-speck 

 at its hinder base, and there is an extra pair of such ocelli 

 between the tentacles and front pair of appendages. Every 

 part of the animal is exquisitely and closely ciliated. 



Shell broad and flattened at its base, and regularly taper- 

 ing to a rather fine point, solid, opaque, not glossy : sculpture, 

 six or seven concentric rows of granules and as many inter- 

 mediate rows of a smaller size on the upper part of the last 

 whorl, nearly as many on the next four whorls, and fewer on the 

 apical or top whorls, the first two of which are ridged instead 

 of granulated; the lowest row in each whorl is much the largest 

 and most prominent, and it forms a consjncuous keel on the 

 basal circumference of the bodv-whorl, and at the suture of 

 the next two whorls ; the granulation arises from the inter- 

 section of spiral ridges by fine and obliquely longitudinal striae ; 

 the base of the last whorl is encircled by about a dozen ridges, 

 which are imbricated, and alternately large and small, as well 

 as decussated by the oblique stria? ; these basal ridges are 

 seldom, or but slightly, granulated : colour whitish, with a 

 very faint tinge of yellow, usually more or less spotted or 

 speckled with reddish-brown or light purple : spire considerably 

 raised, but not elevated, except in the variety ; apex somewhat 

 pointed : whorls 8, flat, and gradually enlarging : suture 

 very slight, only marked by the ridge at the base of each 

 whorl : mouth obliquely squarish : outer lip thin and mostly 

 broken : inner lip white, and folded over the pillar, which is 

 extremely thick and short, with an obscure tubercular excres- 

 cence near the base : inside nacreous, except towards the 

 margin : operculum rather concave, having from twelve to 

 fifteen volutions ; it is membranous, and microscopically reticu- 

 lated, like the scales of certain fishes. L. 0*6. B. 0-6. 



Yar. pyramidata. Smaller, and narrower at the base. 



Habitat : Hard ground, and among Tunicata, from 

 2 to 70 f., on the coasts of Northumberland and Durham, 

 Aberdeen, Orkneys, Shetland, west coast of Scotland, 

 Mull of Galloway (50-145 f., Beechey), and all Ireland. 

 The variety occurs in Hants (Forbes); Shetland, Fish- 

 guard, and Guernsey (J. G. J.); Plymouth (Barlee); 

 west bay of Portland (Forbes and M f Andrew); Corn- 



