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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXIII. 



entire surface of the spire and base appears marked b}^ fine lines of 

 growth and spiral striations. Aperture subquadrate, decidedly chan- 

 neled anteriorl}^; outer lip rendered sinuous by the spiral keels, 

 parietal wall and edge of columella covered by a moderately strong 

 callus. The nuclear structures were described from a young specimen, 

 Cat. No. 19520(), U.S.N.M., which has 10 whorls (the first two nuclear 

 whorls probably being lost), and measures: Length 3.6 mm.-, diameter 

 1.1 mm. The other cotype (Cat. No. 32290, U.S.N.M.) is an adult 

 shell in which the last 11 whorls remain, and measures: Length 

 12.4 mm.; diameter 1.1 mm. 



This species has been known from the west coast under the name of 

 Cerithiopsis assimilata C. B. Adams, a Panamic species, which is a 

 pygmy in size compared with the present form. 



Specimens e.nuii ined. 



BITTIUM (STYLIDIUM ") ESCHRICHTI ICELUM, new subspecies. 



In B. eschric/itl only the early whorls show axial ribs. In the pres- 

 ent form they are well developed on all the turns, weakening only on 

 the last. The type, Cat. No. 15209a, U.S.N.M., was collected by J. G. 

 Swan at Neah Bay, Washington. It has 9 whorls (the nucleus being 

 lost), and measures: Length 1.5 mm.; diameter 5.5 mm. Another 

 specimen, Cat. No. 32209, U.S.N.M., belongs to the Stearns collection 

 and comes from Monterey, California. 



BITTIUM (STYLIDIUM) ESCHRICHTI MONTEREYENSIS, new 



subspecies. 



This form is the southern race of B. eschrichti. It differs from the 

 typical form in being less strongly spirally keeled, much more smooth, 

 more slender, and in every way more elegant than eschrichti. The 

 typical form varies in color from brown to white, and is very rarely 



oThe name Stijlidhun is i)roposed by W. H. Dall, with B. eschrichti Middendorff, 

 as type, in a publication now in press. 



