58 BULLETIN 68, UNITED STATES NATIONAL MUSEUM. 



upon the third, 24 upon the fourth, 28 upon the fifth, 32 upon the 

 sixth and the penultimate turn. Intercostal spaces a little narrower 

 than the ribs, shallow, marked by series of well-impressed pits at 

 the periphery and a second one a little less strong a little anterior to 

 the middle of the space between the sutures; the space between the 

 peripheral and the other series of pits is crossed by about twenty-five 

 equal and equally spaced spiral striations; that between the middle 

 pits and the suture by about forty of equal strength. Sutures poorly 

 defined. Periphery and base of the last whorl well rounded, marked 

 by numerous fine, wavy, spiral striations. Aperture? (outer lip 

 fractured) ; columella strong, with an oblique fold a little below the 

 insertion. 



The type (Cat. no. 160068, U.S.N.M.) comes from Cape St. Lucas. 

 It has 8 post-nuclear whorls and measures: Length 4 mm., diameter 

 1.3 mm. Cat. no. 46502, U.S.N.M., contains a specimen from Boca 

 de los Piedras. 



Named for James Smithson. 



TURBONILLA (STRIOTURBONILLA) GRACILIOR C. B. Adams. 



Plate 4, fig. 6. 



Chemnitzia grarilior C. B. Adams, Ann. Lye. of Nat. Hist. N. Y., vol. 5, 1852, 

 p. 391. 



Shell elongate-conic, milk-white. (Nuclear whorls decollated.) 

 Post-nuclear whorls well rounded, moderately shouldered at the 

 summit; later ones slightly exserted at the summit; marked by 

 slender, sinuous, slightly protractive axial ribs, of which 16 occur 

 upon the first and second, 18 upon the third, 20 upon the fourth 

 to seventh, 22 upon the eighth, 26 upon the ninth, and 32 upon 

 the penultimate turn. Intercostal spaces about twice as wide as the 

 ribs, marked by a double series of pits, the first of which is at 

 the periphery, the second a little posterior to the middle between the 

 sutures. In addition to these pits, they are marked by fine, equal 

 and equally spaced spiral striations of which thirty-one probably 

 occur between the peripheral and median pit and twenty between that 

 and the summit. Sutures well marked. Periphery and base of the 

 last whorl well rounded, marked by the continuations of the axial ribs 

 and numerous fine, well-incised, wavy spiral striations. Aperture 

 rather long, rhomboidal; outer lip fractured; columella moderately 

 strong, slightly curved and somewhat reflected, provided with a weak 

 oblique fold at its insertion. 



Professor Adams's type has served for our description and figure. 

 It has lost the nucleus. The eleven remaining whorls measure: 

 Length 6.1 mm., diameter 1.4 mm. It is in the Amherst College 

 collection and comes from Panama. 



