348 PROf'EEDIXriS OF THE NATIONAL MUSEUM. vui.. xxx. 



one, is situiittHi just posterior to the posterior keel, and this marks the 

 anterior tcrniimition of the strono-, rounded, backward-slantino- axial 

 ribs between the sutures. Sixteen of these ribs occur upon the second, 

 seventeen upon the tifth, and twenty upon the penultimate whorl. 

 Intercostal spaces almost as wide as the ribs, crossed by two strongly 

 impressed, moderately broad spiral lines, which also pass over and 

 somewhat constrict the axial ribs, giving them a dumbell-shaped out- 

 line; the posterior thickened portion is a little wider than the anterior 

 one. The space between these two deeply impressed lines is crossed 

 by about eight minute, subequally spaced spiral striations. Periphery 

 of the last whorl deeply sulcate, crossed by numerous closely spaced 

 axial striations, keel anterior to the periphery almost as strong as the 

 one posterior to it; the third keel is a little anterior to the middle of 

 the base and is rather low and broad; the space between it and the 

 keel above is gently rounded and finely axially striated, which is also 

 true of the space between this keel and the umbilical area. Aperture 

 moderately large, suboval, otiuse at the junction of the outer lip and 

 columella; posterior angle ol)tuse, outer lip thin, irregular in outline, 

 showing the external sculpture within; columella short, curved, stout, 

 beai-ing a strong, acute, oblique fold a little anterior to its insertion; 

 parietal wall covered by a thin callus. 



There are two lots of this species in the Berlin collection, both from 

 Japan; one. No. 1446, containing two specimens, was received from 

 H. Adams, and it is one of these that wq have here described and 

 figured. This specimen has nine post-nuclear whorls and measures: 

 long. 4.4 mm.; diam. 1.5 mm. The other belongs to the Ptetel col 

 lection. 



ODOSTOMIA (TRABECULA) TANTILLA A. Adams. 

 Plate XXII, lig. 3. 

 I'liripilliKi tnntilhi A. Adams, .lour. Linn. Soc. London, VII, 18().i, j). ^. 



Shell small, slender, turrited, milk-white. Nuclear whorls small, 

 strongly ol)Iif|uely innnersed in the first post-nuclear whorl, only a 

 portion of the last solution is visible. Post-nuclear whorls strongly 

 shouldered, moderately rounded, rather high between the sutures, and 

 appearing .somewhat constricted at this point, marked by strong, 

 rounded, backward slanting axial ribs, which render the summits of 

 the whorls strongh' crenulate; fourteen of these ribs occur upon the 

 second, twenty-three upon the fourth, and thirty-two upon the penul- 

 timate whorl. Intercostal spaces about twice as wide as the ribs, 

 crossed between the sutures by five subequally spaced, raised spiral 

 threads, the posterior one of which is a little farther from the summit 

 than it is fi-om its adjacent fellow; it is also a little less .strongly 

 developed than the rest. The ribs and spiral thivads thus form a 

 series of meshes or reticulations. Periphery and base of the last 



