124 BULLETIN 68; UNITED STATES NATIONAL MUSEUM. 



TURBONILLA (DUNKERIA) StJBANGULATA Carpenter. 

 Plate 12, fig. 11. 

 Dunkeria subangulata Carpenter, Cat. Mazatlan Shells, 1856, p. 434. 



Shell elongate-ovate, white. Nuclear whorls two, forming a moder- 

 ately elevated spire, whose axis is at right angles to that of the suc- 

 ceeding turns, in the first of which it is about one-third immersed. 

 Post-nuclear whorls strongly rounded, obliquel}^ shouldered at the 

 summit, marked by slender, vertical, axial ribs, of which 20 occur 

 upon the first, 22 upon the second and third, and 24 upon the penulti- 

 mate turn. In addition to the axial ribs, the whorls are crossed by 

 four slender, spiral cords between the sutures and by a fifth at the 

 periphery and five on the base. The spaces inclosed by the ribs and 

 cords appear as round pits. Periphery and base of the last whorl 

 well rounded. Aperture suboval; outer lip thin; columella some- 

 what twisted and reflected; parietal wall covered with a thin callus. 



An adult and a young specimen are on tablet 2008, Liverpool collec- 

 tion, British Museum. The adult has five post-nuclear whorls and 

 measures: Length 2.8 mm., diameter 0.93 mm. 



TURBONILLA (DUNKERIA) ANDREWSI, new species. 

 Plate 12, figs. 7, 7a. 



Shell small, conic, light chestnut, umbilical area white. Nuclear 

 whorls two and one-half, forming a depressed helicoid spire, whose 

 axis is at right angles to that of the succeeding turns, in the first of 

 which it is about one-third immersed. Post-nuclear whorls well 

 rounded, moderately contracted at the suture, with a sloping shoulder 

 which extends over the posterior third between the sutures, marked 

 by slender, well-rounded, slightly retractive axial ribs, of which 18 

 occur upon the first, 20 upon the second and third, 22 upon the fourth, 

 and 32 upon the penultimate turn. Intercostal spaces about one and 

 one-half times as wide as the ribs upon all but the last whorl, marked 

 by five spiral series of broad pits, which are wide as the five cord-like 

 interspaces which they bound and which render the ribs somewhat 

 tuberculate at their junction. Sutures well impressed. Periphery 

 and base of the last whorl well rounded, the latter marked by the con- 

 tinuation of the axial ribs, which extend feebly to the umbilical area, 

 and six spiral cords which grow successively a little narrower from the 

 periphery to the umbilical area. Aperture oval; posterior angle 

 acute; outer lip thin, showing the external sculpture within; colu- 

 mella rather thick, reenforced by the base; parietal wall covered by a 

 thin callus. 



The type (Cat. no. 162696 U.S.N.M.) comes from Panama. It has 

 six post-nuclear whorls and measures: Length 2.9 mm., diameter 

 1 mm. 



