670 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



CERITHIOPSIS (CERITHIOPSIS) BAKERI, new species. 



Plate 46, fig. 10. 



Shell of medium, size, chestnut brown. Nuclear whorls 3i, well 

 rounded, smooth, forming a styliform apex. Postnuclear whorls 

 well rounded, narrowly, tabulatedly shouldered at the summit, and 

 decidedly contracted anterior to the third keel, marked by rather 

 slender axial ribs, of which 18 occur upon the first to fourth, 20 

 ujDon the fifth, 22 upon the sixth, and 2-i upon the last turn. Inter- 

 costal spaces about 1^ times as wide as the ribs. In addition to the 

 axial sculpture the whorls are marked by three strong spiral keels 

 of which the first, which is considerably weaker than the rest, is at 

 the summit. These keels are about as wide as the spaces that sepa- 

 rate them and are much stronger than the axial ribs. The junctions 

 of the axial ribs and the spiral keels form tubercles. The tubercles 

 on the first keel are well rounded, while those on the second and third 

 are truncated posteriorly and slope gently anteriorly. Periphery of 

 the last whorl marked by a deep spiral groove which is as wide as 

 that separating the median from the third keel. This groove is 

 crossed by the continuations of the axial ribs which stop at the 

 anterior termination of the groove. Suture strongly channeled. 

 Base moderately long, slightly concave, marked by a very strong 

 spiral keel immediately anterior to the peripheral groove. The 

 anterior border of this keel is limited by a slender incised line. A 

 second low, weakly developed spiral cord encircles the middle of the 

 base between the basal fasciole, which is a mere slender thread at the 

 insertion of the columella, and the keel immediately anterior to the 

 periphery. Aperture of irregular shape, decidedly channeled an- 

 teriorly; posterior angle obtuse; outer lip thin, rendered sinuous at 

 the edge by the strong external sculpture ; inner lip decidedly flexuose, 

 reflected over and adnate to the base ; parietal wall covered with a 

 moderately thick callus. 



The type. Cat. No. 223049, U.S.N.M., was collected by Dr. Fred 

 Baker in 7-10 fathoms, south of Coronado Island, California. It 

 has 7^ostnuclear whorls and measures — length, 4.2 mm. ; diameter, 

 1.5 mm. 



CERITHIOPSIS (CERITHIOPSIS) HELENA, new species. 

 Plate 46, fig. 2. 



Shell very small. Nuclear whorls 4|, light yellow, slightly 

 rounded, separated by a moderately constricted suture forming an 

 acicular apex. Postnuclear whorls chestnut brown, excepting the 

 first keel which is white on all the whorls, tabulatedly shouldered at 

 the summit, moderately rounded and strongly constricted below the 



