50 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.49. 



columella short, strongly curved and decidedly reflected over and 

 appressed to the base; parietal wall covered with a thick callus, which 

 joins the posterior angle of the aperture to the reflected edge of the 

 columella, rendering the peritreme complete. 



The type and 2 specimens, Cat. No. 168605, U.S.N.M., come from 

 San Diego, California. The type has 6 postnuclear whorls and meas- 

 m'es: Length, 6.3 mm.; diameter, 2.5 mm. 



The following specimens have been examined: 



Cat. No. 168605, U.S.N.M., 3 specimens from San Diego, California, 

 one = figured type. Cat. No. 158771, U.S.N.M., 2 specimens from San 

 Pedro, California, dredged in 10 fathoms (type of A. oldroydi Dall.). 

 Cat. No. 128355, U.S.N.M., 8 specimens from San Pedro, California 

 (beach drift and also Hving). Cat. No. 151732, U.S.N.M., 4 speci- 

 mens from San Pedro, California. Cat. No. 213368, U.S.N.M., U.S.B.F. 

 station 2932, 20 specimens off Coronados, California, in 20 fathoms, 

 on gray sand and broken shell bottom. Cat. No. 271643, U.S.N.M., 

 U.S.B.F. station 4347, off Point Loma Light, California, in 55-58 

 fathoms, on fine gray sand, broken shell, sponge, and mud bottom. 

 (One specimen.) 



RISSOINA LAPAZANA, new species. 

 Plate 30, fig. 6. 



Shell of medium size, milk white, excepting a single narrow periph- 

 eral band of golden brown. Nuclear whorls large, a little more 

 than two, well rounded, forming a mammilated apex. Postnuclear 

 whorls well rounded, appressed at the summit, overhanging, and 

 marked by about 14 feebly developed, distantly spaced axial ribs 

 which are obsolete on the fu-st and last turns. These ribs are about 

 one-third as wide as the spaces that separate them. In addition 

 to the axial ribs the whorls are crossed by subequal and subequally 

 spaced, sinuous, spiral threads of which 7 occur on the first, 8 on the 

 second, 11 on the third and fourth, and about 16 on the last turn. 

 Of these the primary threads have been split usually on their mid- 

 dle by the intercalation of incised lines. The lines sepai-ating these 

 cords are narrower than the cords. Sutures well impressed. Periph- 

 ery of the last whorl well rounded. Base short, well rounded, 

 marked by about 10 low, broad, spiral cords. Aperture large; 

 outer lip very effuse, thin, showing the external sculpture within; 

 inner lip strongly curved, thin, reflected over and appressed to the 

 base. 



The type. Cat. No. 21 1410, U.S.N. M., was dredged by the U.S. Bureau 

 of Fisheries steamer Albatross at station 2823 in 26^ fathoms on broken 

 shell bottom off La Paz, Gulf of California. It is a perfect specimen 

 having almost 6 postnuclear whorls and measures: Length, 6 

 mm. ; diameter, 2 mm. 



