no. 1823. MOLLUSKS OF THE GENUS CERITIflOPSIS—BARTSCII. 



355 



well impressed, rounded pits. Suture moderately constricted, show- 

 ing the posterior edge of the first basal keel in the early whorls. 

 Periphery of the last whorl marked by a sulcus as wide as those that 

 separate the keels on the spire, and the continuation of the axial ribs. 

 Base short, well rounded, marked with three slender spiral keels 

 which are situated on the posterior two-thirds and separated by 

 shallow channels. The first of these is crossed by slender continua- 

 tions of the axial ribs. The space immediately about the base of the 

 columella is free of sculpture excepting fine, incremental lines. Aper- 

 ture subquadrate, decidedly channeled anteriorly; posterior angle 

 acute; outer lip rendered sinuous by the external sculpture; col- 

 umella very broad at base, stout, somewhat twisted and curved and 

 the edge reflected. 



Doctor Carpenter's type (Cat. No. 148236, U.S.N.M.) was collected 

 by J. G. Swan at Neah Bay, Washington, and measures: Length 9.2 

 mm., diameter 2.6 mm. 



Specimens examined. 



Catalogue 

 No. 



' 148236 

 32218 

 14S23C 

 32398 

 56007 



Locality. 



Neah Bay, Washington 



Vancouver Island 



Monterey, California 



Montery Harbor, California. 

 Monterey, California 



Number of 

 specimens. 



1 Type. 



CERITHIOPSIS INFREQUENS C. B. Adams. 



Plate 37, fig. 1. 



Cerithium infrequens C. B. Adams, Ann. N. Y. Lye. Nat. Hist., vol. 5, 1852, 

 p. 383. 



Shell small, broadly elongate-conic, blackish-red. Nuclear whorls 

 five, well-rounded, smooth. Post-nuclear whorls marked by three 

 strong, spiral cords which are about half as wide as the spaces that 

 separate them. The first of these is a little anterior to the summit, 

 and the second is a little nearer the first than the third, which is about 

 as far removed from the second as it is from the suture. In addition 

 to the spiral cords, the whorls are marked by decidedly retractive, 

 axial ribs which are about as wide as the cords. Of these ribs, 12 

 occur upon the second, 14 upon the third, 16 upon the fourth and 

 fifth, 18 upon the sixth and seventh, and 20 upon the penultimate 

 turn. The junctions of the axial ribs and the spiral cords form well- 

 rounded tubercles, while the spaces inclosed between them are deep, 

 rounded pits. Suture strongly impressed. Periphery of the last 

 whorl marked by a sulcus as wide as that which separates the third 

 from the second cord and, like it, crossed by the continuations of the 



