DESCRIPTIONS OF NEW MOLLUSKS OF THE FAMILY 

 VITRINELLIDiE FROM THE WEST COAST OF AMERICA. 



By Paul Bartsch, 



Assistant Curator, Division of MoUusks, U. S. National Museum. 



Since publishing the paper on New Molkisks of the Family Vitri- 

 nellidae from the west coast of America,'* which contamed descrip- 

 tions and figures of Vitrinella oldroydi, eslinauri, and alaskensis; 

 Vitrinella (Docomphala) stearnsi and herryi; Cyclostrema xantusi and 

 diegensis; Circulus cosmius and cerrosensis; Cyclostremella californica, 

 and Scissilahra dalli, a number of additional forms have come to 

 hand. One of these, Leptogyra alaskana, from Port Graham, Alaska, 

 was described by the writer in 1910,^ and six additional species from 

 the west coast are considered in the present paper. 



The drawings for the two plates were made by Miss Evelyn G. 

 Mitchell. 



CYCLOSTREMA BALDRIDGEI, new species. 

 Plate 39, figs. 7-9. 



Shell rather large, bluish-white, subdiaphanous. Nuclear whorls 

 two and a thu'd, smooth, forming a decidedly depressed spire. Post- 

 nuclear whorls with a strong, broad, rounded keel at the periphery 

 and another almost as strong about one-third of the distance between 

 the periphery and the summit, where it forms a decided shoulder. 

 The space between the appressed summit and the shoulder is marked 

 by twelve subequal and subequally spaced, spiral cords, the spaces 

 between which are crossed by very slender, retractive, axial threads; 

 the latter are about one-fourth as wide as the spaces which separate 

 them, while the spaces between them are only about one-half the 

 width of the spiral cords. The space between the peripheral keel 

 and the strong shoulder is crossed by nine subequal and subequally 

 spaced spiral cords, and the continuations of the axial threads. 

 Here the spiral sculpture is not quite as strong as on the upper sur- 

 face, and the spaces inclosed between the axial riblets and the spiral 

 threads are more or less quadrangular pits. Base well rounded, 



aProc. U. S. Nat. Mus., vol. 32, no. 1520, pp 167-176. 

 6 Nautilus, vol. 23, 1910, pp. 136-137, pi. 11, figs. 4-6. 



Proceedings U.S. National Museum, Vol. 39— No. 1785. 



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