1917.] NATURAL SCIENCES OF PHILADELPHIA. 181 



flat, separated by a channelled suture, angular above and below it, 

 the lower angle becoming more prominent on the penult whorl, 

 forming a keel which continues at the periphery of the last whorl, 

 which is rather strongly concave above it, and slightly so below. 

 The surface is marked with faint growth-lines and many unequal 

 spiral striae. The aperture is ovate, somewhat oblique; columella 

 thick, bearing a stout oblique plait above. 



Length 1.85, diam. 0.9, length of aperture 0.6 mm.; very nearly 

 5 whorls. 



Type No. 3096, A. N. S. P. 



This species is related to 0. circumvinda, but is wider, with a 

 stronger peripheral carina, a stronger columellar plait, and not so 

 many whorls. 



The spiral sculpture is indicated rather than drawn in the figures 

 of this species and the next. The spiral strise are very low, rounded, 

 unequal and unevenly spaced, but somewhat coarse and barely 

 visible with a good hand lens. 



As it cannot readily be fitted into any of the sections of Odostomia, 

 we propose the new section Goniodostomia, for Odostomias without 

 axial ribs, having a peripheral keel and spiral striation, the columellar 

 plait emerging, nucleus wholly immersed. Type 0. superans. 



Odostomia (Goniodostomia) circumvinota n. sp. 



The shell is rimate, slowly tapering to the obtuse summit, the 

 embryonic whorls immersed, first visible whorl convex, turned in at 

 the tip; subsequent whorls flat, narrowly excavated above and nar- 

 rowly shouldered below the suture, which is therefore deeply chan- 

 nelled; last whorl angular or subcarinate at the periphery. Sculpture 

 of faint growth-lines and rather sparse unequal, low, spiral strise. 

 Aperture ovate; columella thin, bearing a short fold above. 



Length 1.75, diam. 0.65, aperture 0.5 mm.; 5f whorls. 



Type No. 3097, A. N. S. P. 



Somewhat like 0. vexator, but the suture is decidedly more chan- 

 nelled and the last whorl is carinate. In shape but not in sculpture 

 it resembles the subgenus Eulimastoma. It is more slender than 

 0. superans. 



Odostomia (Parthenina 1) cyclocephala n. sp. 



Shell lanceolate, thin, with a large helicoid nucleus of 1| whorls; 



subsequent whorls sculptured with small vertical ribs narrower than 



their intervals, becoming obsolete at the periphery; over ribs and 



intervals there are delicately engraved spiral lines, of which 17 may 



13 



