MARGARITA. 287 



MiDDENDORFF, Mai. Rossica, ii, p. 69. — M. hellcina Fabr., Krause, 

 Archiv f. Naturg. 1885, p. 262. 



This species is very abundant. It may be known by the smooth 

 surface, lightly spirally striate around the umbilicus, the rather 

 narrow umbilicus, etc. 



T. horecdls Phil, w^as proposed for American specimens ; Phil- 

 ippi's figures are copied on PL 39, figs. 49, 50. His figure of 

 T. margnrita Mont, on PL 39, fig. 63. M. vulgaris Leach (PL 39, 

 fig. 46,) is the same as the form called campanulata by Morse. 



31. grocnlandica ' Beck ' of Sowerby, in Reeve, f. 6, and of Philippi, 

 Conchyl. Cab. t. 37, f. 5, are prol:)ably additional synonyms of this 

 protean species. The figures of Sowerby and of Philippi are copied 

 on PL 44, fig. 22, and 21. 



M. ACUMINATA Sowerby. PL 39, fig. 55 ; pi. %Q, fig. 6. 



Shell orbicular, thin, whitish ; spire acuminate, whorls 5, rounded, 

 smooth ; suture distinct ; a|)erture orbicular ; umbilicus small. 



Alt. "55, diam. '5 in. (Soivb.) 



Arctic Ocean. 



31. acuminata SowB., Mai. and Conch. Mag. i, p. 26 (1838). — 

 Conch. 111., f. 7. — SowB. Jr. in Reeve, Conch. Icon., f. 13. — Trochus 

 bembe.v Phil., Conchyl. Cab., p. 286, t. 42, f. 5. — 31. acuminata 

 MiGH. & Ad., Bost. Journ. N. H. iv, p. 46, t. 4, f 15. 



The 3L acuminata Mighels and Adams (pi. 66, fig. 6), taken in 

 the Gulf of St. Lawrence, is described as follows : 



Shell small, orbicular, subconical, thin, of a grayish-white or 

 russet color , spire acuminate ; whorls 4, well-rounded, smooth, 

 covered with a thin semitransparent ejiidermis, strise of growth very 

 fine and compact ; suture well impressed ; aperture orbicular, 

 considerably oblique, beautifully iridescent within ; operculum 

 horny, spiral. Alt 6], diam. 6] mill. (31. & A.) 



The single specimen of this American form before me is much 

 more depressed than the figure given by Sowerby. It seems to be 

 specifically distinct. 



M. vAHLii MoUer. PL 39, figs. 58, 59. 



Shell small, conoidal, very smooth, shining, hyaline, pearly ; 

 whorls 4-4i, convex, the last subangular ; umbilicus narrow. (Phil.) 



This is the smallest of the 3Iargarita species known to me. The 

 shell approaches a j^retty flat cone in form, for the upper whorls are 



