398 BULLETIN OF THE 



transversely wrinkled. The rest of the body (excepting the base of the foot) 

 is finely granulose, or furnished with minute close-set, rounded, short, project- 

 ing points or papillae. 



The head is moderately long and rounded much as in most Trochidce ; the 

 muzzle rounded, its distal end forming a well-defined moderately papillose 

 rounded-ovate disk; the mouth is about in the centre, with a deep sulcus ex- 

 tending in the median line below and breaking the continuity of the margin. 

 The tentacles are long, slender, subcylindrical, rather bluntly pointed, and 

 wrinkled in a longitudinal direction, probably from contraction induced by 

 the alcohol. The eyes are small, round, and black; the cutis above them has 

 a small central perforation, so that the office of a lens must be performed by 

 the water having access to the cup-shaped cavity within. There is no lens 

 present. 



The upper surface of the foot is widely expanded at the sides, from a point a 

 little behind the front edge of the foot to the posterior extremity. This expan- 

 sion, though differing from the homologous organ in the TrocJiidce in its form 

 and arrangement, is identical with the epipodium in that family. It is broad, 

 thin, and entire, and fringed, as is the free edge of the mantle, with a single 

 row of small short slender papillae. This extends back to the extreme termina- 

 tion of the foot, the two epipodial expansions not uniting behind. There are 

 no cirri, tentacular filaments, lappets, or other projections to the epipodial mar- 

 gin, as in ScissurellidcB or Trochidce. The upper surface of the epipodium is 

 continuous with the upper surface of the foot, and is depressed and more finely 

 granular than the outer part. About the centre of the upper surface of the 

 body behind the shell is the operculigerous lobe, which is of a circular form 

 and about 7.0 mm. in diameter. The depression between the epipodia extends 

 to the posterior termination of the foot. In life the epipodia are thin and ex- 

 tended, like a supplementary mantle, and are kept closely applied to the shell 

 as if supporting it; in this respect differing from the same organs in the Tro- 

 chidce, where they extend, like organs of touch, freely into the water on each side 

 of the body, and only incidentally touch the shell. 



The anterior margin of the foot is rounded, and perhaps double, but the 

 duplication is evidently not deep, and is hardly visible in the contracted speci- 

 mens before me. This organ is very muscular in this group. The posterior 

 end is not very acutely pointed. 



The operculum is nearly circular, small for the size of the shell, its greatest 

 diameter being only 7.5 mm., and its smallest diameter 7.0 mm. Within 

 this range it has ten narrow whorls, smooth or lightly striated with incre- 

 mental lines on both sides, of a brown color, thicker toward the margin and 

 having its central point impressed slightly from the exterior. 



The length of the (contracted) foot is about 33 mm., the width between 

 the tentacles is about 7 mm., and the tentacles are about 10 mm. long. The 

 mantle is thin, its edge resembles that of the epipodia, but, as preserved, the 

 individual papillae of the fringe seem a little larger and stouter. In life they 

 extend along the margin of the notch, and are visible from the outside. Be- 



