182 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



HOLOSPIRA (HOLOSPIRA) NELSONI Pilsbry. 



The U. S. National Mu.seum has 43 specimens of this species, Cat. 

 No. 187785, collected by E. W. Nelson and E. A. Goldman at Sierra 

 Guadelupe, Coahuila, Mexico, at an altitude of 9,500 feet. The fol- 

 lowing table gives measurements of twenty individuals: 



Measurements of Holospira (Holospira) nelsom. 



HOLOSPIRA (HOLOSPIRA) OAXACANA, new species. 

 Plate IV, lig. 5. 



Shell quite large, strong, cylindric conic, white. Nuclear whorls 

 two, moderately large, well rounded, very minutely granulose. Ter- 

 minal cone evenl}^ tapering, the last six whorls of the spire quite cylin- 

 drical. The whorls of the cone are a little more rounded than those 

 of the cylindrical portion; they are all crossed by obliquelj'^ backward 

 slanting thread-like riblets, which are a little more strongly developed 

 and more distantly spaced on the early and last whorls than the middle 

 ones. There appear to be about 56 of these riblets on the fourth, 160 

 upon the eighth, and 100 upon the penultimate whorl in the t^'pe. 

 Sutures well marked. Periphery of the last whorl slightly angulated. 

 Base short and well rounded. The periphery and base are crossed by 

 the continuations of the riblets, which extend undiminished into the 

 rather deep umbilical rimation. Last whorl free for about one milli- 

 meter. Aperture semioval, the parietal wall representing the short 

 diameter of the oval white. Peristome broadly expanded ])ut not 

 reflected, white. Internal column ver}^ slender, hollow, with an obso- 

 lete submedian twist. In the penultimate whorl this twist is replaced 



