WEST AMEKICAN PYRAMIDELLID MOLLUSKS. 87 



Of tJiese pits the peripheral one and the three anterior to the one at 

 the summit are stronger than the rest; the space separated by the 

 second and third below the summit is a little wider than the rest, and 

 the pits biting in the ribs render these somewhat nodulose at this 

 place. Sutures well impressed. Periphery of the last whorl well 

 rounded. Base moderately long, well rounded, marked by the 

 continuations of the axial ribs which extend feebly to the umbilical 

 region, and about eight weakly incised spiral lines, those nearest the 

 periphery being somewhat interrupted by the ribs. Aperture sub- 

 oval; posterior angle acute; outer lip thin, sho^\^ng the external 

 markings within; columella slender, slightly twisted and very 

 oblique. 



The type (Cat. no. 206869, U.S.N.M.) comes from San Diego. It 

 has ten post-nuclear whorls and measures: Length 5.8 mm., diameter 

 1.7 mm. Cat. no. 163260, U.S.N.M., contains another specimen, 

 collected by Mrs. Oldroyd at San Pedro, California. 



TURBONILLA (PYRGISCUS) ANTESTRIATA Dall and Bartsch. 



Plate 8, figs. 5, 5a. 



TurhonUla {Pyrgiscus) antestriata Dall and Bartsch, Proc. U. S. Nat. Mus., 

 vol. 33, 1907, pp. 506, 507, pi. 45, figs. 4, 4a. 



Shell large and strong, light brown. Nuclear whorls two and 

 one-half, small, smooth, forming a depressed rounded hehcoid spire, 

 which projects somewhat beyond the left side of the outline of the 

 spire of the later whorls and has its axis at a right angle to the axis 

 of these, being about one-fourth immersed in the first turn. Post- 

 nuclear whorls slightly rounded, ornamented by low, rounded, 

 narrow, vertical axial ribs which become decidedly flattened and 

 enfeebled near the summit of the turns; there are 9 of these ribs on 

 the second, 20 upon the fifth, and 28 upon the penultimate post- 

 nuclear turns. Intercostal spaces about double the width of the ribs, 

 shallow, rounded, crossed by 6 equal and equally spaced, strongly 

 incised, spiral lines which extend stronger upon the sides of the ribs 

 and feebl}^ over their summits. In addition to this sculpture, the 

 spire is marked by many fine lines of growth and many fine spiral 

 striations between the incised lines. Sutures well marked, simple. 

 Periphery of the last whorl subangulated, marked by the feeble con- 

 tinuations of the axial ribs, wliich disappear at the periphery. Base 

 short, marked by 11 continuous, equal, strong, incised spiral lines 

 which are more closely spaced above the umbilical area than at the 

 periphery; the space between the first basal incised line and the first 

 supraperi])heral one being a little wider than the space inclosed 

 between the spiral lines on the spire. Aperture subquadrate, outer 

 lip thin, showing the external sculpture within; columella almost 

 straight and vertical, slightly revolute. 



