MARGARITA. 293 



represent very young shells ; fig. 29, pi. 60 is the var. grandis of 

 Morch ; fig. 25. pi. 44, is the M. maxima of Sowerby ; fig. 20, pi. 44 

 is copied from the original figure of T. corneus Kiener. The 

 typical form is figured on pi. 64, figs. 53, 54. The T. BI:I:< IIHYANUS 

 Martens is figured on pi. 44, figs. 26, 27. I am unable to tind char- 

 acters separating it from cinerea. 



Var. MARGARITIFERA Friele. PL 66, fig. 100, 1. 



The shell broad coniform, rather thin, with a strong mother-of-pearl 

 luster ; 5 whorls, connected by a shallow suture. The sculpture 

 consists of 4 to 5 angular spiral ribs on the ultimate whorl, and 

 2 to 3 on the spire whorls ; apex smooth ; on the lower surface of the 

 shell, which is rather flattened, close spiral striae occur ; the shell 

 otherwise is smooth, except that toward the aperture there are some 

 faint lines of growth ; umbilicus narrow. Alt. 5i, diam. 5? mill. 



This is the most beautiful shell found in the Arctic Ocean. It has 

 a luster equal to the most brilliant pearl. The umbilicus is strik- 

 ingly narrower than in the typical form. (Friele). 



Arctic Ocean, East of Greenland, 350 fms. 



M. SCHANTARICA Middendorff. PL 47, figs. 84-88. 



Shell perforate, conoid-convex, apex obtuse, thin, dark slate-gray, 

 buff around the umbilicus, with spots of dull black below the 

 periphery ; whorls convex, encircled by stride ; last whorl large, 

 scarcely angulated, base a little convex, suture distinct; aperture 

 large, suborbicular, peristome subcontinuous ; columellasubproduced 

 at base ; umbilicus partly closed by the columellar lip. 



Alt. 21, diam. 22 mill. ; alt. 21, diam. 19 mill. (Midd.). 



Schantar Is., Sea of Ockhotsk. 



Trochus schantaricus MIDD., Mem. de 1'Acad. de St. Petersb. vi, 

 ser., viii, p. 413 ; Reise in Siberiens, ii, Zoologie, p. 204, t. 18, f. 1-7 

 (1851) ; Beitr. zu Mai. Rossica, ii, p. 85 (1847). T. modestus MIDD., 

 Beitr. zu einer Mai. Rossica, ii, p. 85, t. 10, f. 16-18 (1847). Mar- 

 garita modesta Midd. SOWB., Conch. Icon., f. 23. 



The line-like, elevated longitudinal striae of the sculpture are only 

 weak, but are pretty sharply defined. They encircle the whorls at 

 regular distances from each other, and are about one-fourth the 



