486 



PROCEEDINGS OF THE ACADEMY OF 



[1898. 



MARGARITA SHARPII, A NEW ALASKAN GASTROPOD. 



BY HENRY A. PILSBRY\ 



Margarita Sharpii n. sp. 



Shell thin, of low-conoid form, with extremely broad funnel- 

 shaped umbilicus and very rapidly expanding whorls. Color, dull 

 salmon or brick-pink, becoming ashy on the spire and within the 

 umbilicus. Sculpture, numerous spiral cords and threads, which on 

 the spire are strong, alternately smaller, then with a tertiary series 

 intercalated, the whole becoming less pronounced on the last whorl, 

 where by further intercalation of threads the spirals 

 become very numerous in some individuals, and in 

 others mostly obsolete ; the base with close, strong 

 spiral cords outside the edge of the umbilicus; the 

 whole surface with fine, crowded and somewhat 

 lamellar growth-stria?, the spire with some spaced 

 coarser radial riblets. Whorls 44, very rapidly ex- 

 Fig. 1. panding, the last at the aperture about three times 

 the width of the preceding (seen from above) ; gently convex ; peri- 

 phery angular ; base convex, the umbilical region broadly excav- 

 ated, nearly as large as the aperture. Aperture large, very oblique, 

 salmon colored within, with brilliant green reflections, but having a 

 wide border within the lip appearing dull whitish from in front, 

 but showing red and white reflections seen from below. Peristome 

 thin, deeply excised in the umbilical region, above the excision pro- 

 duced forward as a low wall curving around the umbilical edge, 

 continuing as far as the posterior termination of the outer lip. Alt. 

 7.5, greater diam. 14, lesser 11 mm. 



Operculum concave externally, with about 8 closely coiled whorls 

 with slightly free overlapping edges. 



Dutch Harbor, Unalaska (Dr. B. Sharp, June 21, 1896). 



The relations of this species are with M. umbilicalis Brod. & Sowb. 



and 31. vorticifera Dall. 1 The former of these is a Greenland species 



with the glossy surface and rounded whorls of the North Atlantic 



Margaritas. M. vorticifera is found in the Aleutian Islands, and 



■Manual of Conchology, XI, p. 288, pi. 59, f, 48-50, 



