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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



mental lines only. Sutures channeled. Aperture irregular, large, 

 decidedly channeled and somewhat twisted anteriorly; posterior 

 angle obtuse; outer lip moderately thin, showing the external 

 sculpture witliin by transmitted light; columella very strongly 

 curved and revolute ; parietal wall covered with a thick callus which 

 renders the peritreme complete. A strong, white varix is present 

 about a quarter turn beliind the lip. 



The type (Cat. No. 213024, U.S.N.M.) was collected by Mrs. T. 

 S. Oldroyd at San Pedro, California. It has eight postnuclear 

 whorls and measures : Length, 3.8 mm.; diameter, 1.6 nrni. Another 

 specimen from the same locality is in Mrs. Oldroyd' s collection. 



DIASTOMA STEARNSI, new species. 



Shell elongate-conic. Early whorls and columella light chestnut 

 brown, the remaining creamy wdiite. Nuclear whorls decollated, 

 only the last two volutions remaining, which are well rounded and 

 smooth. Postnuclear wdiorls strongly rounded, marked by low, well- 

 rounded, vertical axial ribs which are about as 

 wide as the intercostal spaces; of these ribs six- 

 teen occur upon the first, and twenty-four upon 

 the remaining whorls. In addition to these ribs, 

 the whorls are marked by seven spiral cords, 

 which are about as wide as the spaces that sepa- 

 rate them and render the axial ribs nodulose. 

 The cord at the summit is a little wider than 

 the rest, likewise the space that separates it 

 from the adjacent cord and this renders the 

 summit of the whorls crenulated. The first 

 subperipheral cord is apparent on all the whorls 

 and forms the seventh one, between the sutures. 

 The axial ribs usually encroach upon this only 

 feebly, the nodulations therefore being less 

 marked than on the spiral cords posterior to 

 it. Sutures strongly constricted; periphery of 

 the last whorl and base well rounded, the lat- 

 ter marked by six equal and equally spaced 

 spiral cords which are a httle less wide than the 

 spaces that separate them. Aperture not quite 

 complete in our specimen, broadly ovate, chan- 

 neled anteriorly; posterior angle acute; outer lip thin, showing the 

 external markings within; columella moderately strong, somewhat 

 twisted, curved, decidedly reflected; parietal wall glazed with a 

 thick callus. 



The type (Cat. No. 32212, U.S.N.M.) has seven postnuclear whorls 

 and measures: Length, 9 mm.; diameter, 3 mm. It comes from San 

 Diego and is named for the late Dr. R. E. C. Stearns. 



Fig. 4.— D I a s t o m a 



STEAKNSI BARTSCH. 



