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 ; tig. 20, pi. 44 

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

 typical form is figured on pi. 64, figs. 53, 54. The T. beech eyanus 

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

 acters separating it from einerea. 



Var. MARGARiTiFERA Friele. PI. 66, fig. 100, 1. 



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

 luster ; 5 whorls, cimnected 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. 5j, diam. 54 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, S50 fms. 



M. scHANTARiCA Middeudorff. PI. 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 an gulated, base a little convex, suture distinct; aperture 

 large, suborbicular, peristome subcontinuous ; columella subproduced 

 at base ; umbilicus partly closed by the columellar lip. 



Alt. 21, diam. 22 mill. ; all. 21, diam. 19 mill. (Jlidd.). 



Schantar Is., Sea of Ockhotsk. 



Trochus schantaricus Midd., Mem. de I'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 {\d>Al).— Mar- 

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



The line-like, elevated longitudinal strise 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 



