230 PBOCBEDINOS OF TEE NATIONAL MUSEUM. vol.39. 



marked like the upper surface, with the sculpture a little less pro- 

 nounced. Umbilicus open; parietal wall showing ten equal and 

 equally spaced spiral cords, which are as wide as the spaces that 

 separate them, the latter being crossed by feeble continuations of 

 the axial riblets. Aperture subcircular; outer lip rendered some- 

 what angular by the two keels; columella evenly curved. 



The type (Cat. No. 214100, U.S.N.M.) comes from the Gulf of Cali- 

 fornia. It has one and a third post-nuclear whorls and measures: 

 greater diameter 4.5 mm. It was collected by Mrs. E. E. Johnson 

 and at her request is named for Mrs. Maria Baldridge, of Los Angeles, 

 California. 



CYCLOSTREMA MIRANDA, new species. 



Plate 39, figs. 1-3. 



Shell small, subdiaphanous, depressed. Nuclear whorls two, 

 depressed helicoid, smooth. Post-nuclear turns one and a third, 

 appressed at the summit, marked above with three strong, spiral 

 cords, one of which is at the periphery, while the other two divide 

 the space between the periphery and the summit into three equal 

 areas. The space between the summit and the first spiral cord 

 is decidedly concave, while the space between the first spu'al 

 cord and the median one is very slightly concave, that between the 

 median and the peripheral cord being well rounded. Axially, the 

 upper surface of the shell is marked by about sixty-two slender, 

 well-developed, equally-spaced riblets, which are about half as wide 

 as the spaces that separate them. These riblets are decidedly 

 retractively curved between the summit and the first keel, less so 

 between the first and the median keel, while between the median 

 and the peripheral one they are practically vertical. The junctions 

 of riblets and keels are not nodulose. Periphery of the last 

 whorl strongly angulated; base marked by two spiral cords, one of 

 which bounds the broad, open, funnel-shaped umbilicus and is a 

 little weaker than the other, which appears as a very strong cord 

 half-way between it and the periphery. In addition to these spiral 

 cords, the base is marked by the undiminished continuations of the 

 axial riblets, which become bifurcated here and extend deep within 

 the umbilicus. Aperture very large, ovate, very oblique, the colu- 

 mellar border being considerably behind the outer lip ; the posterior 

 and anterior angles are acutely angulated; outer lip thin, showing 

 the external sculpture within; columella slender, decidedly curved, 

 the free edge continuing to the posterior angle of the aperture, ren- 

 dering the peritreme complete. 



The type (Cat. No. 211108, U.S.N.M.) measures: greater diameter, 

 2.1 mm. It and two other specimens, in ]\Irs. Oldroyd's collection, 

 were collected by Mrs. Oldroyd at San Pedro, California. 



