no. "1823. MOLLUSKS OF THE GENUS CERITHIOPSIS—BARTSCH. 347 



oval, decidedly channeled anteriorly; posterior angle obtuse; outer 

 lip rendered sinuous by the external sculpture, which is apparent 

 within the aperture; columella very short, very broad and curved, 

 with the free edge reflected; parietal wall glazed with a thin callus. 



The type (Cat. No. 3775, U.S.N.M.) comes from Panama. It has 

 six postnuclear whorls and measures: Length 2.1 mm., diameter 

 0.7 mm. 



Named for the late Prof. C. B. Adams. 



CERITHIOPSIS (CERITHIOPSIDA) DIEGENSIS, new species. 



Plate 40, fig. 4. 



Shell small, broadly elongate-conic, chestnut brown. Nuclear 

 whorls two and one-half; the first half smooth ; the next turn has about 

 20 slender, axial threads; while the last whorl has about 32 axial 

 threads and 2 spiral cords, the first of which is on the middle of the 

 whorl, and the second one about halfway between this and the suture. 

 The early post-nuclear whorls have 2 spiral cords, like the last of the 

 nuclear whorls. Beginning with the third turn, a slender, spiral 

 cord appears immediately anterior to the summit, increasing rapidly 

 in size until, on the last volution, it is about equal to the other two. 

 In addition to the spiral sculpture, the whorls are marked by strong, 

 axial ribs equaling the spiral cords in strength. Of these ribs, 16 

 occur upon all but the penultimate turn, winch has 18. The junctions 

 of the axial ribs and spiral cords form prominent, cusp-like tubercles, 

 while the spaces inclosed between them form large, squarish pits. 

 Suture strongly impressed. Periphery of the last whorl marked by 

 a strong keel, separated from the supraperipheral cord by a sulcus 

 as wide as that which separates the supraperipheral from the median 

 cord and, like it, crossed by the continuations of the axial ribs which 

 terminate at the posterior border of the peripheral cord. Base short, 

 concave, bearing a slender fasciole at the insertion of the columella. 

 Entire surface of spire and base crossed by numerous fine, incremental 

 lines. Aperture subquadrate, very strongly channeled anteriorly; 

 posterior angle obtuse; outer lip rendered sinuous by the external 

 sculpture, which is apparent in the aperture; columella short and 

 broad, twisted, the free edge reflected; parietal wall glazed with a 

 thin callus. 



The type (Cat. No. 160079, U.S.N.M.) comes from San Diego, 

 California. It is not quite mature, has six post-nuclear whorls, and 

 measures: Length 4 mm., diameter 1.6 mm. Another specimen (Cat. 

 No. 162044, U.S.N.M.) comes from San Clemente Island, California. 



