TRICHOTROPIS. 363 



brown ; it is ovate-subtrigonal, being broad above, and 

 acntangnlar below. There is some disposition to expand 

 in the acute and simple outer lip, which abruptly juts out 

 in a straightish line from the body at rather an obtuse 

 angle, turns down at rather more than a rectangle in a 

 scarcely convex curve, and eventually slants in an almost 

 rectilinear direction to the peaked anterior extremity. No 

 sculpture adorns the moderately incurved inner lip ; the 

 edge of the compressed and narrowly reflected pillar lip is 

 not appressed, so that there seems a kind of subumbilical 

 chink behind it. The operculum is much wrinkled across, 

 and is small for the size of the aperture ; in the white 

 examples it is dirty yellow, but becomes darker in the 

 stained ones. Our British specimens are usually five or 

 six lines long, and three or four lines broad. 



The variety acuminata is an interesting one. The spire 

 is so peculiarly produced as considerably to exceed the 

 length of the body, on which latter the inferior keels are 

 almost, if not wholly, obsolete, so that the conspicuous 

 carinse alone are present. 



Animal entirely white, head lunate, tentacula with 

 subulate terminations and thickened sides for half their 

 lengths, bearing the black eyes on the extremities of the 

 thickenings. Siphon well marked, but not projecting; 

 foot broad, truncated and angulated in front, obtuse, and 

 rather short behind. Operculum somewhat polygonal, 

 corneous, presenting marked indications of the successive 

 layers Avhich form segments of a circle in the inner side of 

 the lateral and rather inferior nucleus. 



This is one of our rarer and more local British shells, 

 and is a member of our boreal fauna. It is found in 

 various depths of water from fifteen to eighty fathoms, 

 and more, frequenting various kinds of sea bottom. Tt 



