284 TROCHID.E. 



and numerous very fine lines ; on the base these are so faint as to 



be usually imperceptible without a magnifier ; these, with rather 



coarse lines of growth, somewhat prominent at intervals, 



often produce an indented or cellular appearance on the sur- 



face ; umbilicus large and deep, bounded by a sharp, angu- 

 M.obscu- lar ridge ; aperture circular ; lip simple and sharp ; within iri- 

 descent ; operculum horny, multi-spiral. Height, five tenths 

 of an inch ; diameter of base, seven twentieths of an inch. 



Found rather plentifully in fishes caught off Nahant. All of New 

 England coast (^Stunpson) ; Fishing Banks (^Willis). 



It has a general resemblance to M. cinerea, but it is more solid, 

 less elevated, less angular, revolving lines fewer and less elevated, 

 the base smoother, the aperture more simple and circular, and the 

 color very different. 



It may perhaps be identical with M. costellata, Sowerby, described 

 in the " Malacological and Conchological Journal," No. 1, and fig- 

 ured hi his " Conchological Illustrations " {Margaritci) , fig. 15. On 

 inspection, Mr. Sowerby, though not having his shell at hand for 

 comparison, regards it as distinct from M. costellata. 



When the exterior is worn off, the shell beneath is found to be of 

 a brilliant silvery lustre, with crimson reflections, rendering it one 

 of the most attractive shells found in our waters. 



Margarita acuminata. 



Shell small, orbicular, thin, whitish ; spire pointed ; whorls four, rounded, 

 smooth; suture strongly impressed; aperture orbicular, iridescent within; um- 

 bilicus small. 



Marr/arifa acuminata, Mighels and Adams, Best. Journ. Nat. Hist. iv. 46, pi. 4, fig. 1.5 

 (1842). — Stimpson, Check Lists, 4. 



Shell, small, orbicular, sub-conical, thin, of a grayish-white or 

 russet color ; spire acuminate ; whorls four, well rounded, smooth, 

 Fi 546 covered with a thin, semi-transparent epidermis ; striae of 

 growth very fine and compact; suture well im])ressed ; aper- 

 ture orbicular, considerably oblique, beautifully iridescent 

 M. aru- within ; operculum horny, spiral. Height, twenty-five hun- 

 mmata. ^Y(n\.t\\'f^ of au iuch ; diamctcr, twenty-six hundredths of an 

 inch ; divergence, eighty degrees. 



Gulf of St. Lawrence, taken from the stomach of a codfisli, by 

 Mr. Foster, in the summer of 1841. Only a single specimen was 

 found, which is in the cabinet of J. W. Mighels. 



