346 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 40. 



truncated posteriorly on the second and third cords, sloping gently 

 anteriorly. The spaces inclosed between -the spiral cords and axial 

 ribs are rectangular pits, having their long axes parallel to the spiral 

 sculpture. The axial ribs extend prominently to the appressed 

 summit of the whorls, forming a series of pits above the first spiral 

 cord. Suture strongly constricted, showing the posterior edge of 

 the base in all the turns. Periphery of the last whorl marked by a 

 sulcus not quite as wide as that which separates the second and third 

 cords and, like it, crossed by the continuations of the axial ribs. 

 Base moderately long, smooth except for incremental lines, the 

 peripheral sulcus giving the posterior edge of the base a decidedly 

 angulated aspect. Aperture irregularly, broadly oval, decidedly 

 channeled anteriorly; posterior angle very obtuse; outer lip rendered 

 sinuous by the external sculpture; columella strongly curved and 

 twisted, the free edge reflected; parietal wall covered with a moder- 

 ately thick callus. 



The type is a perfect specimen of nine post-nuclear whorls and 

 measures: Length 7.7 mm., diameter 1.8 mm. It and seven addi- 

 tional specimens (Cat. No. 195205, U.S.N.M.) came from the Lower 

 San Pedro Series, Deadmans Island, California. 



CERITHIOPSIS (CERITHIOPSINA) ADAMSI, new species. 



Plate 41, fig. 1. 



Shell minute, elongate-conic, dark brown. Nuclear whorls three 

 and one-half, of which the first one and one-half are smooth, while 

 the succeeding two are marked by slender, axial riblets, 30 of which 

 occur upon the last and 24 upon the preceding turn. Post-nuclear 

 whorls moderately rounded, marked by three spiral cords, of winch 

 the first, which is at the summit, is more poorly developed than the 

 other two, which are equal. These two cords divide the remainder 

 of the whorls between the sutures into three equal areas. In addi- 

 tion to the spiral sculpture, the whorls are marked by axial ribs 

 which are almost as strong as the spiral cords. Of these ribs, 16 occur 

 upon the second and third, 18 upon the fourth, and 24 upon the 

 penultimate turn. The junctions of the axial ribs and spiral cords 

 form well-rounded tubercles, while the spaces inclosed between them 

 are strongly impressed, rectangular pits. Suture strongly impressed. 

 Periphery of the last whorl marked by a broad sulcus which equals 

 the sulcus betwen the supraperipheral and the median cord in width 

 and, like this, is crossed by the continuations of the axial ribs, winch 

 extend to the posterior edge of the first basal cord. Base moderately 

 long, well rounded, marked by two strong, spiral cords, the stronger 

 of which is immediately below the peripheral sulcus, while the other 

 is a little posterior to the insertion of the columella. Aperture broadly 



