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RISSOIA. 345 



R. SEMICARINATA, Folin. PL 70, fig. 58. 



Whitish, subdiaphanous, whorls flatly convex, spirally cingulate. 



Length, 1*5 mill. 



New Caledonia. 

 R. ROBUSTA, Dall. PL 71, figs. 76, 77. 



Shell smooth, scarcely rimate, with impressed suture; whorls 4 

 5, slightly convex, purplish with whitish bloom, with very fine 

 spiral striae particularly towards the base. Length, 5 mill. 



Aleutian Is. ; Plover Bay, E. Siberia. 



Dr. Dall calls the normal form var. Martyni, so that that name 

 may be substituted in the event of robusta, Lea being recognized. 



Var. SCIPIO, Dall. Fig. 77. 



Shell more slender. Perhaps males, and the stouter ones females. 

 The occurrence of a certain number of intermediate specimens is 

 mentioned. 



R. CERINELLA, Dall. PL 71, fig. 79. 



Narrowly rimate, smooth, not polished. Length, 3 mill. 



Behring Sea. 



Close to C. proxima, Alder, but differs in the absence of spiral 

 striation and in having less truncate apex, and one less whorl. 



C. ALEUTICA, Dall. PL 71, fig. 78. 



Slightly umbilicated, smooth, with faint growth-lines, no spiral 

 sculpture, suture distinct, whorls moderately convex ; brownish, the 

 slightly expanded edge of the aperture blackish. Length, 3'5 mill. 



Aleutian Is. 



More slender and smaller than C. minuta, Totten, less slender 

 and without the sculpture of C. aeuleus, Gould. 



R. EXILIS, Tryon. PL 71, fig. 80. 



Whorls 6, convex, with well-marked suture, aperture small, sur- 

 face covered with slight revolving striae, light .brown. 



Length, 3 '3 mill. 



San Diego, Cal., on salt-water grass. 



R. STIMPSONI, Smith. PL 71, fig. 73. 



Whorls 7, convex, with deep suture, distinctly wrinkled by growth 

 lines, apex obtuse, shell thin, dark brown. Length, 5'7 mill. 



Greenport, Long Island, New York. 



I am not acquainted with this species, of which two specimens 

 occurred to the author. 



