350 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 40. ~ 



closely spaced axial threads and fine, spiral lirations in the inter- 

 costal spaces. Post-nuclear whorls slightly rounded, marked by 

 three tuberculate spiral cords of which the posterior one is at the 

 summit, the anterior at some little distance posterior to the suture, 

 while the third is about median between the two. The posterior cord 

 is very poorly developed on the early whorls, in fact quite absent on 

 the first volution, but grows steadily in size until, in the last volution, 

 it is as strong as the other two. In addition to the spiral cords, the 

 whorls are marked by vertical axial ribs which are as strong as the 

 spiral cords and render the junction with them tuberculate. Of these 

 ribs, 14 occur upon the first to third, 16 upon the fourth, 18 upon the 

 fifth and sixth, 20 upon the seventh to ninth, 22 upon the tenth, and 

 24 upon the penultimate turn. The tubercles of the posterior cord 

 are well rounded, that of the median slightly truncated posteriorly, 

 while on the anterior cord they appear truncated in the middle, sloping 

 gently anteriorly and very suddenly posteriorly. Sutures strongly 

 constricted; periphery of the last whorl marked by a sulcus which is 

 as wide as the spaces that separate the keels on the spire and like 

 them is crossed with the continuations of the axial ribs. Base short, 

 well rounded, marked by four spiral keels which grow gradually 

 weaker and a little closer spaced from the periphery to the umbilical 

 area, the last one forming a slender basal fasciole about the insertion 

 of the columella. In addition to the spiral sculpture, the base is 

 marked by numerous fine incremental lines. Aperture rhomboidal; 

 decidedly channeled anteriorly; posterior angle acute; outer lip thin, 

 rendered wavy by the external sculpture; columella moderately long, 

 stout, decidedly curved, and somewhat twisted. 



The type (Cat. No. 195200, U.S.N.M.) has lost the first two nuclear 

 whorls, the thirteen remaining whorls measuring: Length 6.9 mm., 

 diameter 1.8 mm., and comes from 8 miles off Point Loma Light, 

 California, U. S. Bureau of Fisheries station 4310, and was dredged 

 in 71 to 75 fathoms on gray mud and fine sand bottom. The early 

 nuclear whorls were described from a young specimen (Cat. No. 

 195201, U.S.N.M.) from Whites Point, San Pedro Bay. Three other 

 specimens (Cat. No. 195202, U.S.N.M.) were dredged in 12 to 15 

 fathoms off San Diego. 



CERITHIOPSIS (CERITHIOPSIDELLA) ALCIMA, new species. 

 Plate 39, fig. 2. 



Shell elongate-conic, chestnut brown. Nuclear whorls three and 

 one-half, small, moderately rounded, separated by a well-impressed 

 suture; the first whorl smooth; the second and third marked by 

 slender, protractive, curved, axial ribs, of which 18 occur upon the 

 second and 20 upon the third. Intercostal spaces about twice as 

 wide as the axial ribs, crossed by about 15 slender, spiral lirations. 



