no. 1823. 2IOLLUSKS OF THE GENUS CERITHI0P8IS—BARTSCH. 



349 



which intersect the riblets in oblique even curves at right angles. The 

 transition from the nuclear to the post-nuclear sculpture is abrupt, 

 the three chief tuberculate spiral keels being present from the very 

 beginning of the first post-nuclear turn. On the first four post- 

 nuclear turns the posterior spiral keel is less developed than the rest, 

 but it increases with each succeeding turn and finally becomes the 

 strongest of the three. The tubercles on the early whorls are almost 

 round and slope abruptly, concavely posteriorly and are gently well 

 rounded anteriorly. On the later whorls they are oblong, with their 

 long axis vertical. Channels separating the spiral keels about as 

 wide as the keels on the early whorls, less so in the later turns, curved 

 by the low, broad, strong, backward-slanting, axial riblets. The 

 spaces between these ribs and the spiral keels appear as rounded 

 pits. Sutures well impressed. Periphery of the last whorl marked 

 by a strong spiral keel. Base well rounded, marked by three equal 

 and equally spaced, spiral keels separated by equally wide and strong 

 channels. The entire surface of the spire and base are marked by 

 microscopic lines of growth and spiral striations. Aperture sub- 

 quadrate, posterior angle obtuse, decidedly channeled at the junction 

 of the short, thick, somewhat twisted columella and outer lip. 



This description is based upon two specimens, cotypes, Cat. No. 

 195196, U.S.N.M. One has the nucleus and eleven post-nuclear 

 whorls, and has furnished the description of the nucleus. This 

 measures: Length 7.3 mm., diameter 2.3 mm. The other has lost 

 its nucleus and probably the first two post-nuclear turns, and meas- 

 ures: Length 9 mm.; diameter 2.9 mm. 



Specimens examined. 



Catalogue 

 No. 



160S70 

 56012 

 56008 

 160077 

 195197 

 • 195196 

 195190 

 153057a 

 198601 

 109365 

 195171 

 198757 

 32392 

 198972 



Locality. 



Monterey, California 



do 



do 



Catalina Island, California 



San Pedro Bay, California 



Whites Point, San Pedro Bay, California 



San Pedro Bay, California 



Government Jetty, San Diego, California 



San Diego, California 



do 



San Diego, California (dredged 12-15 fathoms). 



Southern California 



Todos Santos Bay, Lower California 



do 



Number of 

 specimens. 



1 Cotypes. 



CERITHIOPSIS (CERITHIOPSIDELLA) ANTEFILOSA, new species. 



Plate 40, fig. 9. 



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

 and one-half, moderately rounded, separated by a poorly defined 

 suture; the first one smooth, the next two and one-half with slender 



