NO. 1520. 



NEW VITRINELLID MOLLUSKS—BARTSCH. 



171 



of the last whorl well rounded, the first half showing continuations of 

 the ribs, the rest being smooth. Base moderate!}" rounded with a 

 fairly strong spiral keel which is situated about one-third of the way 

 toward the umbilical angle from the periphery. Umbilicus much 

 narrower than T^ stearnsi^ its outer edge terminating in a blunt angle. 

 Columellar wall decidedly concaved, the inner half marked b}' a series 

 of strong riblike nodules as in V. stearnsl. Aperture decidedly 

 oblique, subcircular; outer lip thin; columella ver}^ thick, concaved, 

 provided with a moderately strong callus which bends back into the 

 umbilicus. 



The type, Cat. No. 192686, U.S.N.M., and another specimen in the 

 collection of Mr. S. S. Berry were dredged by that gentleman in 12 

 fathoms, off Del Monte, Monterey Bay, California. It has 4 whorls 

 and measures: Greater diameter, 2.2 umi.; lesser diameter, 1.7 mm.; 

 altitude, 1 mm. Another specimen of this species. Cat. No. 192687, 

 U.S.N.M., was collected by Mrs. T. S. Oldroyd at San Diego, 

 California. 



CYCLOSTREMA XANTUSI, new species. 



Shell small, transparent, with moderately elevated spire. Nepionic 

 whorls If, well rounded, smooth. The succeeding turns are marked 

 by a strong peripheral cord and another spiral cord which is situated 



Fig. 6. — CYCLOSTREMA XANTrSI. a, TOP VIEW; h, SIDE VIEW; C, BASAL VIEW. 



a little nearer the summit than the periphery of the whorls. In addi- 

 tion to this spiral sculpture there are many (about 48 on the last turn) 

 regular, equally spaced, low riblets, which coincide with the lines of 

 growth and are about one-third as wide as the spaces that separate 

 them. Periphery of the last whorl strongl}" angulated b}" the spiral 

 cord. The base is marked by three spiral keels — one at the edge of the 

 umbilicus, the other two divide the space between this and the periph- 

 eral keel into three equal parts. The riblets of the upper surface 

 continue equally strong over the space between the peripheral and the 

 tirst basal keels, but between this and the second basal keel the}^ 

 become decidedly enfeebled, while they are almost absent between the 

 second keel and the one that bounds the umbilicus. Umbilicus broadly 

 open. Columellar wall of the last whorl well rounded and marked by 

 three equally spaced spiral threads, the inner one of which is decidedly 



