28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 9I 



rather strongly rounded, marked by strong, slightly sinuous axial 

 ribs, which become slightly enfeebled near the summit of the whorls 

 but extend conspicuously across the posterior sulcus. These ribs are 

 about as wide as the spaces that separate them. Twelve occur upon 

 the first to third, 14 upon the fourth, and 16 upon the last turn, on 

 which they extend across the base to the columellar area, where they 

 become evanescent. In addition to the ribs the entire surface is 

 marked by rather well developed incremental lines. The spiral sculp- 

 ture is absent on all the whorls but the last. On this, five slender, 

 feeble spiral threads are present anterior to the sutural sinus. Suture 

 well impressed. Base moderately long, well rounded, marked by seven 

 feebly developed spiral cords that grow stronger from the periphery 

 anteriorly. Columella short and stubby, marked by five strong spiral 

 cords. Aperture decidedly channeled anteriorly and posteriorly, the 

 posterior channel deep and slightly thickened at the edge. There is 

 a strong varix about one fourth of a turn behind the aperture. Outer 

 lip protractive from the posterior sinus to the anterior notch, inner lip 

 reflected over the columella as a heavy callus that has almost the aspect 

 of a distinct lip, parietal wall covered by a heavy callus that develops 

 into a strong nodule near the posterior angle. 



Type. — U.S.N.M. no. 430853, collected from station 10 in 120 to 

 160 fathoms between latitude i8°29'2o" N., longitude 66°o5'3o" W. 

 and latitude i8°3o'24" N., longitude 66°04'i5" W. It has 7.2 whorls 

 and measures : Length, 6.2 mm ; diameter, 2.2 mm. 



U.S.N.M. no. 430999 contains two topotypes from the same locality. 



This species is closely related to Syntomadrillia woodringi, from 

 which it can at once be distinguished by its much stouter and fewer 

 spiral cords on the columella and by its more slender nuclear whorls. 



SYNTOMODRILLIA TANTULA, n. sp. 



Plate 8, figs. 2, 3, 6 



Shell small, elongate-conic, pale wax-yellow. Nuclear whorls 1.6, 

 smooth. Postnuclear whorls marked by strong, slightly protractively 

 slanting axial ribs which extend over the posterior sinus, where they 

 become slightly retractively curved but not interrupted. Anteriorly 

 they extend over the rounded periphery and base to the columella. 

 These axial ribs are about as wide as the spaces that separate them. 

 Ten are present on the first three postnuclear whorls, 12 on the fourth, 

 and 14 on the last turn. The spiral sculpture consists of well-incised 

 lines anterior to the posterior sinus, no spiral sculpture being noticed 

 on the latter. Of these lines, 5 are present on the second, 6 on the 



