308 trochid^:. 



arranged diagonally (so as to give the upper surface a par- 

 tially granulated appearance), and minutely but irregularly 

 speckled with flake-white : pallial lappets large and unequal 

 in size, the left one being the smaller and slightly scalloped, 

 the other plain-edged : head semicircular, lineated or wrinkled 

 transversely, closely scalloped at its edge ; front lobes small 

 and white : tentacles white, filiform, very long, slender, flexible, 

 somewhat contractile, and finely setose ; tips blunt : eyes pro- 

 portionally large, seated on angular bulbs or short tubercles 

 (" capable of twisting about in various directions," Montagu): 

 foot lanceolate, thick, rounded at each end, with small angular 

 points at the corners ; edges delicately scalloped ; top fringe or 

 ridge on each side thin and wavy ; sole flake-white : appen- 

 dages 3 on each side, white, issuing from beneath the dorsal 

 ridge ; they resemble the tentacles, and are nearly as long and 

 more pointed ; each of the filamental appendages or vibracula 

 has at its base a small cup-shaped tubercle. The animal is 

 exquisitely ciliated all over. 



Shell turreted but not much elevated, solid, opaque, of 

 rather a dull hue : sculpture, numerous fine spiral ribs, which 

 are often alternately larger and smaller, and vary in size and 

 their relative proximity ; the surface is crossed by minute and 

 close-set oblique strise ; the base of the shell, and usually the 

 upper part of each whorl, are encircled by a more or less dis- 

 tinct keel, giving an angulated appearance : colour varying from 

 white to citron, closely spotted or speckled with reddish-brown 

 (the spots being arranged in spiral lines), and often marked with 

 more or less irregular dark longitudinal blotches or streaks : 

 spire moderately raised : whorls 6 or 7, their convexity being 

 in an inverse ratio to the height of the spire ; they gradually 

 increase in size : suture frequently slight, deeper in more 

 turreted specimens : mouth oblique, in consequence of the 

 upper lip advancing considerably beyond the lower ; it is 

 notched in the middle of the outer lip, and channelled below 

 the pillar : outer lip thin and plain : inner lip thick, folded 

 back on the umbilicus, and furnished in the middle with a 

 slight tooth-like tubercle : inside beautifully iridescent : um- 

 bilicus large but not wide, obliquely excavated, and exposing 

 a considerable part of the inner spire : operculum having from 

 10 to 12 whorls, and mostly becoming concave towards the 

 centre. L. 0-333. B. 0-333. 



Habitat : Oozy ground in the laminarian zone, and 



