122 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXI. 



this band bears small, forward-slanting teeth, the whole resembling 

 the blade of a narrow saw. 



Type. — Epirohia {Propilsbrya) nelsoni, new species. 



EPIROBIA ( PROPILSBRYA) NELSONI, new species. 

 Plate IV, fig. 8. 



Shell subulate, horn colored with white riblets. Nuclear whorls two 

 and one-half, somewhat inflated, smooth under ordinary magnitication, 

 but very minutely granulose when viewed under the compound micro- 

 scope. Later whorls well lounded, crossed by many slender, quite 

 regular, obliquely curved riblets, which are about one- 

 third as wide as the spaces between them. The riblets 

 are less developed on the early whorls than in the mid- 

 dle of the spire; in the middle I counted 11 in the space 

 of 1 millimeter. They are strongest on the penultimate 

 whorl, where only 8 were counted in the space of 1 milli- 

 meter. Periphery of the last whorl somewhat angulated, 

 the angulation becoming less 

 apparent toward the aper- 

 ture. Base rounded, pierced 

 by the small open umbilicus 

 and marked by the continua- 

 tion of the ribs which extend 

 over it and into the umbili- 

 cus. Last whorl solute for 

 al>out li mm. Parietal wall 

 of the solute portion decid 

 edly pinched at about one- 

 third of the way to the left 

 of the posterior lateral angle, 

 which lends the parietal wal 1 

 a sinuous aspect. The so- 

 lute portion of the parietal 

 wall is crossed by the con- 

 tinuation of the ribs of the outer wall, 

 parietal wall representing the short diameter of the oval, angulated 

 at the posterior lateral margin and at the junction of the columella 

 and parietal wall; well rounded anteriorly, showing" the weak parietal 

 fold within. Peristome moderately effuse, but not revolute. Internal 

 column slender, perforate, having a somewhat submedian thread-like 

 fold, which extends throughout the entire spire. In the antipenulti- 

 mate and penultimate whorl, this fold becomes very much enlarged, 

 forming a strong lamella, which extends one-fourth of the waj" across 

 the space between the pillar and the wall. This lamella tapers very 

 rapidlj" both anteriorly and posteriori}'. Transverse septa thin, trans- 



FlG. 7.— IXTERIOB 

 VIEW OF EPI- 

 ROBI.\ NELSONI. 



Fig. 8. — Detail of interior of Epi- 

 robia nelsoni. 



Aperture semi-oval, the 



