348 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 40. 



CERITHIOPSIS (CERITHIOPSIDA) ROWELLI, new species. 

 Plate 40, fig. 6. 



Shell elongate-conic, pale brownish yellow. Nuclear whorls large 

 and tumid extending considerably beyond the lateral outline of the 

 first post-nuclear whorl; the first half volution, smooth, well rounded ; 

 the remaining one and a half decidedly inflated, strongly rounded, 

 crossed by very strong acute axial ribs which are about one-third as 

 wide as the strongly impressed intercostal spaces that separate them. 

 Of these ribs, about 17 are on the last turn. Post-nuclear whorls 

 slopingly shouldered, below the appressed summit marked by three 

 tuberculate, spiral keels which divide the spaces between the sutures 

 into four equal rows. In addition to the spiral keels, the whorls are 

 marked by strong, broad axial ribs, the intersection of which with the 

 spiral keels appear as prominent cusps. Of these ribs, 16 occur upon 

 the first and second, 18 upon the third, 20 upon the fourth and 

 penultimate turn. The individual tubercles of all three keels are 

 truncated posteriorly and slope gently and regularly to the anterior 

 border. The spaces inclosed by the axial ribs and spiral keels are 

 well impressed, squarish pits. Suture strongly constricted; periph- 

 ery of the last whorl marked by a prominent, smooth keel; base 

 short, almost flat, smooth, excepting lines of growth and a slender 

 fasciole about the base of the columella. Aperture irregularly 

 ovate; decidedly channeled anteriorly; posterior angle acute; outer 

 lip rendered decidedly sinuous by the external sculpture; columella 

 very broad at base, somewhat twisted and sinuous, the anterior edge 

 slightly reflected; parietal wall glazed with a thin callus. 



The type (Cat. No. 15559) was taken from Haliotis b}^ Rowell, 

 exact locality not known. The label bears the legend "West coast of 

 North and Middle America." It probably came from California. 

 It has six post-nuclear whorls and measures: Length 4.5 mm., 

 diameter 1.8 mm. 



CERITHIOPSIS (CERITHIOPSIDELLA) COSMIA Bartsch. 



Plate 38, fig. 7. 

 Cerithiopsis cosmia Bartsch, Proc. TJ. S. Nat. Mus., vol. 33, 1907, pp. 180-181. 



Shell elongate-conic, variegated with various shades of brown, white, 

 and wax yellow. Nuclear whorls three and one-half, slender, lending 

 the apex a mucronate appearance. First nuclear whorl smooth, sec- 

 ond crossed by feeble axial riblets. The riblets increase considerably 

 in size in the remaining turns, where they are very regularly developed 

 and evenly spaced. These riblets are strongly protractive as they pass 

 from summit to suture, the extremity at the suture being considerably 

 in advance of the extremity at the summit. In addition to the verti- 

 cal riblets, microscopic, crinkly lines appear in the intercostal spaces 



