31 Q TROCIIIDjE. 



one on the inner side of each ; the veil is a continuation of the 

 foot-crest and " when erected has the appearance of an awning 

 or semipavilion hanging over the disk of the muzzle " (Clark): 

 tentacles filiform, long and tapering, marked across with pur- 

 plish-brown (in southern examples alternately violet and 

 white) rings, and sometimes down the middle with a dark 

 line ; they are covered with whitish cilia, and contractile : eyes 

 placed on short angular stalks which are white in southern 

 examples : foot thick, broader and rounded in front, and 

 bluntly pointed behind, with finely and closely ciliated edges ; 

 sole yellow ; the ridge or crest on the upper part of each side 

 is irregularly fringed ; lateral appendages 3 on each side, with 

 frequently several shorter intermediate ones ; the principal 

 filaments resemble the tentacles, but are usually shorter and 

 slighter (white in southern examples) ; each is sheathed, and 

 has sometimes at its base a small tubercle on each side, which 

 are occasionally of a darker colour and might be taken for 

 ocelli or eye-specks. 



Shell varying in height, according to the nature of habitat 

 (being more depressed when living among Laminarice than 

 among stones between tide-marks or in the coralline zone), 

 solid, opaque, and of a rather dull hue : sculpture, 1 or 8 thread- 

 like spiral ridges on the upper part of the body whorl, with 

 often one or two finer striae between each ridge, and about a 

 dozen fine ridge-like striae on the under side ; the intermediate 

 surface is covered with numerous very minute longitudinal 

 hair-like striae, which are set obliquely; the basal keel is 

 blunt, but distinct : colour light grey or pale yellowish, varie- 

 gated by close-set narrow and oblique streaks of dark purplish- 

 brown, the continuity of which is mostly interrupted by the 

 spiral ridges, so as to give a somewhat speckled appearance : 

 spire more or less raised, with a blunt apex :' vjhorls 6 or 7 ; 

 the lower ones are flattened and expanded, and the top ones 

 rounded and moderately convex : suture narrow, although 

 rather deep and sometimes channelled : mouth large, squarish 

 and oblique, as in other species : outer lip bevelled to a thin 

 edge : inner lip thick, somewhat reflected, especially over the 

 upper part of the umbilicus, and usually furnished in the 

 middle with a slight tubercular projection : inside highly na- 

 creous except near the edge of the mouth, which is white and 

 dull: umbilicus rather small and narrow, obliquely funnel- 

 shaped and colourless, not exposing the spire of the penulti- 

 mate whorl : operculum having from 10 to 12 volutions, which 



