566 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



than its fellow, forming weak nodules at its junctions with the 

 axial ribs. Suture strongly impressed. Periphery of the last whorl 

 marked by a slender, plain cord, wliich is covered 

 by the summit of the succeeding turn. The groove 

 between this cord and the anterior series of tuber- 

 cles is crossed by the extensions of the axial riblets. 

 Base very short, marked by a slender, shallow, 

 spiral groove, which bounds the peripheral cord 

 anteriorly. The space between the groove and 

 the insertion of the columella is slightly concave, 

 marked only by lines of growth. Aperture rhom- 

 boidal, decidedly channeled anteriorly; posterior 

 angle obtuse; outer lip sinuous; columella strong, 

 short, twisted and provided with a strong, obhque 

 fold at its anterior margin; parietal wall covered 

 with a tliin callus. 



The type (Cat. No. 15342, U.S.N.M.) has ten post- 

 nuclear whorls and measures: Length, 5.7 mm., 

 diameter 2 mm. It comes from Guacomayo, Mex- 

 ico. Another specimen (Cat. No. 32286, U.S.N.M.) comes from the 

 Gulf of California. 



Fig. 1.— Eumeta in- 

 tercalaris carpen- 

 TER. 



EUMETA, BIMARGINATA C. B. Adams. 



Cerithium bimarginatum C. B. Adams, Ann. Lye. Nat. Hist. New York, 1852, 

 pp. 375-376. 



Shell elongate-conic, wax-yellow, except the posterior row of 

 tubercles, which are light brown. Nuclear whorls four and one-half; 

 the first half turn smooth; the remainder well rounded, 

 separated by a constricted suture, marked by curved, 

 quite regular, slender, distantly spaced, axial riblets, of 

 which 16 occur upon the second, 18 upon the third, and 

 20 upon the last turn. Post-nuclear whorls concave in 

 the middle, marked by two spiral cords, the first of 

 which is at some little distance anterior to the summit, 

 leaving a narrow, plain band at the summit, while the 

 other is equally remote from the suture, the space be- 

 tween the two being about double the width of the spi- 

 ral cord and the plain space at the summit. In addition 

 to the spiral cords, the whorls are marked by well- 

 rounded axial ribs which are very feeble posterior to 

 the spiral cord at the summit. Of these ribs, 18 occur 

 upon the first to tliird, 20 upon the fourth and fifth, 22 upon the 

 sixth and seventh, and 24 upon the penultimate turn. These ribs 

 are expanded"where they meet the spiral cords, forming well developed 

 tubercles at their junction. The spaces inclosed between the spiral 



Fig. 2.— Eumeta 

 bimarginata 

 C. B. Adams. 



