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PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol. 40. 



prominent cusps which are suddenly truncated posteriorly, and slope 

 gently anteriorly until they fuse with the general surface of the shell. 

 Sutures well impressed. Periphery and base of the last whorl well 

 rounded, marked by about nine feeble spiral cords of which the first 

 two immediately below the periphery are the strongest. Aperture 

 subquadrate, channeled anteriorly; posterior angle acute; outer lip 

 rendered somewhat sinuous by the external sculpture; columella 

 moderately long, twisted, and reflected ; parietal wall glazed with a 

 thin callus. 



Gabb's type came from the Lower Pleistocene deposits at Santa 

 Barbara, Calif oinia. The specimen described and figured (Cat. No. 

 165231, U.S.N.M.) is a fossil from Santa Barbara. It has 10 post- 

 nuclear whorls (having lost the nucleus and probably the first post- 

 nuclear turn) and measures: Length 8.3 mm., diameter 2.9 mm. 



Specimens examined. 



BITTTIUM (LIROBITTIUM) ASPERUM LOMAENSE, new subspecies, 



Plate 56, fig. 2. 



Shell similar to B. asperum Gabb, but differing in being uniformly 

 smaller, more slender, and in having more ribs. A specimen of 

 B. asperum with 10 post-nuclear whorls measures: Length 8.1 mm., 

 while one of B. a. lomaense of the same number of whorls measures 

 7.1 mm. B. a. lomaense is a living representative of B. asperum, 

 which is a post-Pliocene species. 



The type (Cat. No. 195130,U.S.N.M.) and 21 specimens were dredged 

 at U. S. Bureau of Fisheries station No. 4310, in 71-75 fathoms, off 

 Point Loma Light, California, on gray mud and fine sand bottom. 

 The type has ten post-nuclear whorls and measures: Length 7.1 

 mm., diameter 2.3 mm. Cat. No. 23744, U.S.N.M., contains 24 speci- 

 mens dredged in 30 fathoms off Santa Catalina Island, California. 



BITTIUM (LIROBITTIUM) CERRALVOENSE, new species. 

 Plate 55, fig. 1. 



Shell elongate-conic, white. Nuclear whorls one and one-half, 

 having two cords which divide the space into three equal parts. 

 Post-nuclear whorls appressed at the summit, decidedly overhang- 



