32 PKOCEEDINGti OF THE NATIONAL, MUSEUM Vol.70 



MARGARITES (LIRULARIA ?) SMITHI, new species 



Plate 4, figs. 7, 11, 12 



Shell minute, rather elevatedly helicoid. white. Nuclear whorls 

 one and a half, well rounded with a carina about one-third of the 

 distance between the summit and the suture, anterior to the summit. 

 Postnuclear whorls well rounded, marked by the continuation of the 

 nuclear carina, which forms a rather strong cord and a slender cord 

 about midway between this and the summit, and two strong cords 

 which divide the space between the carina and the suture into equal 

 spaces. Between these three cords a lesser one is present. From the 

 third cord, which almost marks the periphery on the last whorl, the 

 base curves gently to the rather open umbilicus. The base is marked 

 by spiral cords, which increase steadily in strength from the pe- 

 riphery to the umbilical angle; the last five are very strongly de- 

 veloped. The umbilical wall appears to be free of sculpture, except- 

 ing incremental lines. The spire and base of the shell are marked 

 by strong incremental lines, which in crossing the base, form slight 

 riblets between the spiral cords. Aperture, oval; posterior angle, 

 obtuse; outer lip, thin; peristome complete; operculum multispiral,^ 

 horny. 



The type. Cat. No. 340814, U.S.N.M., was collected in 10 fathoms 

 off China Point, Monterej?^, California, by A. G. Smith. It has 2.1 

 postnuclear whorls and measures, altitude, 1.6 mm. ; greater diameter, 

 1.7 mm. 



SOLARIORBIS ARNOLDI, new species 



Plate 6, figs. 7, 8, 9 



Shell large, lenticular, semitranslucent, bluish white. Nuclear 

 whorls 1.2, well rounded, smooth. Postnuclear whorls moderately 

 rounded, almost appressed at the summit, the first marked by six 

 interrupted lines of pits and two slender spiral striations near the 

 summit. As the whorls progress the pits become more or less fused 

 into incised spiral lines, of which 7 occur upon the second and 24 

 upon the last whorl. In addition to the spiral sculpture, the whorls 

 are marked by slender, somewhat irregular retractively slanting axial 

 threads. Periphery of the last whorl slightly obtusely angulated. 

 A rather broad band immediately below the periphery is devoid of 

 spiral sculpture. Base broadly openly umbilicated; the posterior 

 half marked by incised spiral lines which leave the elements between 

 them as moderately broad, flattened cords and numerous lines of 

 growth. The latter are a little rougher at the umbilical angle than 

 on the flattened base. The umbilicus shows all the turns within it. 

 Aperture decidedly oblique, oval; posterior angle with a slender 

 sinus; outer lip thin, showing the external sculpture by transmitted 



