no. 1820. MOLLUSKB OF THE GENUS BITTIUM—BARTSGH. 405 



above sculpture, the entire surface of the spire and base is crossed by 

 numerous fine lines of growth and exceedingly fine, spiral striations. 

 Aperture subquadrate, channeled anteriorly; posterior angle obtuse; 

 outer lip rendered sinuous by the external sculpture; columella short, 

 stout, somewhat twisted, and reflected parietal wall glazed with a 

 thin callus. 



There are ten specimens of this species (Cat. No. 15501, U.S.N.M.) 

 collected by Swan at Neah Bay, Washington, which bear the legend 

 "type." One of these (fig. 1) has seven post-nuclear whorls, and 

 measures: Length 7.8 mm., diameter 3 mm. Another (fig. 2) meas- 

 ures 7 mm. long. 



BITTIUM (LIROBITTIUM) MUNITUM MUNITOIDE, new subspecies. 

 Plate 53, fig. 4. 

 This is the southern race of Bittium munitum. It differs from 

 B. munitum proper in being smaller and in having many more ribs, 

 as many as 40 occurring upon the last whorl. The type, one of 115 

 specimens (Cat. No. 152164, U.S.N.M.) from San Pedro, California, 

 has ten post-nuclear whorls, and measures: Length 8.2 mm., diameter 

 2.8 mm. Another lot from Whites Point, San Pedro Bay, California, 

 contains 106 specimens. Four specimens were dredged in 50 fathoms 

 off San Pedro, California. 



BITTIUM (LIROBITTIUM) ASPERUM Gabb. 



Plate 56, fig. 3. 

 Turbonilla aspera Gabb, Proc. Acad. Nat. Sci. Phila., 1861, p. 368; 

 =Bittium asperum Gabb, Pal. California, ser. 2, p. 72, pi. 2, fig. 20, 1869; 

 —Bittium barbarense Bartsch, Smiths. Misc. Coll. (Quarterly Issue), vol. 50, 1907, 



pt. 4, p. 28, pi. 57, fig. 15. 

 Not Bittium? asperum Carpenter, Ann. Mag. Nat. Hist., ser. 3, vol. 17, p. 276, 



1866; =Bittvum rugatum Carpenter. 



Shell elongate-conic, creamy white. Nuclear whorls small, a little 

 more than one, marked by two moderately strong, spiral cords, one a 

 little posterior to the periphery and the other on the middle of the 

 whorl, otherwise smooth. Post-nuclear whorls appressed at the 

 summit, strongly, slopingly shouldered, the first marked by two spiral 

 cords like those on the nuclear whorls, the second showing an inter- 

 calated cord between the two, leaving the posterior half of the whorls 

 free of sculpture and with a strong, sloping shoulder. On the suc- 

 ceeding whorls the shoulder is crossed by one and two spiral cords, 

 less strong than those anterior to them. In addition to the spiral 

 sculpture the whorls are marked by somewhat curved, almost vertical 

 axial ribs, which begin on the second whorl and rapidly increase in 

 strength. There are 12 of these ribs on each of the second to ninth 

 turns. The intersections of the axial ribs and spiral cords form 



