582 



PROCEEDINGS OF THE NATIONAL MV8EUM. 



VOL. 39. 



above the suture; on the last whorl an additional slender cord 

 appears between that on the summit and its neighbor. In addition 

 to these spiral cords, the whorls are marked by strong, broad, low, 

 axial ribs, of which twelve occur upon the first and second, fourteen 

 upon the third and fourth, and sixteen upon each of the remaining 

 whorls. The intersections of the spiral cords and 

 axial ribs are nodulose. In addition to these cords 

 and ribs, the entire surface of the shell is marked by 

 numerous, very fine, spiral striations and slender 

 lines of growth. Periphery of the last whorl marked 

 by a sulcus which is as wide as the space between 

 the cords on the spire and is crossed by the slender 

 continuations of the axial ribs. Base well rounded, 

 marked by eight equal and subequally spaced, 

 rounded, spiral cords. Aperture elongate, decidedly 

 effuse at the junction of the outer and basal lips, 

 channeled anteriorly and subchanneled at the pos- 

 terior angle; outer lip thin, rendered somewhat sin- 

 uous by the external sculpture; columella short and 

 twisted; parietal wall covered with a thick callus, 

 which extends over the edge of the columella and 

 renders the peritreme complete. In the two speci- 

 mens before me a strong varix is present a fourth of a 

 turn behind the lip. 

 The description and figure are based upon two specimens (Cat. No. 

 162561, U.S.N.M.) collected by Colonel Jewett in the Lower Pleisto- 

 cene beds at Santa Barbara, CaUfornia. One, a young individual of 

 eight post-nuclear whorls, has furnished the description of the nucleus. 

 The other, which has lost the nucleus and probably the first post- 

 nuclear whorl, having eight post-nuclear whorls remaining, has fur- 

 nished the remainder of the description. The two specimens men- 

 tioned measure : Length, 4.7 mm. ; diameter, 1.5 mm.; and length, 6.5 

 mm.; diameter 2.1 mm., respectively. 



DIASTOMA CHRYSALLOIDEA, new species. 



Shell elongate-conic, pinkish white. Nuclear whorls partly decol- 

 lated, the one remaining, smooth. Post-nuclear whorls appressed at 

 the summit, slopmg evenly from the posterior three-quarters between 

 the sutures posteriorly, falling ofi" rapidly between the sutures on the 

 anterior fourth; marked by broad, low, rounded, distinct axial ribs, of 

 which sixteen occur upon all the whorls. In addition to these ribs the 

 whorls are marked by spiral bands, which are about as wide as the 

 spaces that separate them. Of these bands, four occur upon the sec- 

 ond turn ; the fourth, marking the anterior termmation of the sloping 

 shoulder, is a little stronger than the rest and a little wider spaced. 



Fig. 1.— DiASTOMA 



FASTIGIATA CAR- 

 PENTER. 



