254 INVERTEBRATA OF MASSACHUSETTS. 



It has a general resemblance to M. cintrea, 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 figured 

 in his " Conchological Illustrations" (Margarita) fig. 15. On inspection, 

 Mr. Sowerby, though not having his shell at hand for comparison, re- 

 gards 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. 



MARGARI'TA UNDULA'TA. 



Shell orbicular, low-conical, dark flesh-color, encircled with 

 regularly disposed spiral lines, alternately larger and smaller, 

 coarsely plaited at the sutures. 



FIGURE 162. 

 State Coll., No. 35. Soc. Cab., No. 2277. 



Margarita undulata, SOWERBY; Malacol. and Conchol. Mag., i. 26. Conchol 



Illust., (Margarita), f. 4. 

 Turbo incarnatus, COUTHOUY; Bost. Journ. Nat. Hist., ii. 98, pi. 3, f. 13. 



Shell thin, orbicular, depressed-conical, usually of a bright 

 brownish-red color ; sometimes rose-red, at others pale flesh- 

 colored ; whorls four, convex, somewhat flattened above, undu- 

 lated near the suture by short folds or wrinkles, and encircled by 

 numerous, elevated, smooth spiral lines at uniform distances, and 

 for the most part alternately larger and smaller ; base considerably 

 flattened, of a lighter color, and with finer striae ; umbilicus broad, 

 funnel-shaped, distinctly bounded by a spiral line, and partially 

 covered by the reflected inner lip ; aperture nearly circular, very 

 oblique ; lip sharp, slightly jagged ; throat pearly, with greenish 

 and golden reflections ; operculum thin, horny, multi-spiral. 

 Height T 3 F inch, base T 4 T inch. 



Found in great numbers in the stomachs of fishes, and also 

 alive on Phillips's Beach. Mr. Sowerby received it from the 

 Arctic Ocean. 



