38 PROCEEDINGS OF THE NATIONAL, MUSEUM vol. 6G 



MARGINELLA GUAICA Maury 



• Plate 6, fig. 12 



Marginella yuaica Maury, Bull. Auier. Paleont., vol. 10, no. 42, p. 200, pi. 34, 

 figs. 2, 4, 1925. 



Shell of medium size, biconic, polished, and five whorled. Spire 

 acuminate and about one-fourth the length of shell. Body whorl 

 strongly shouldered below the suture, below which it slightly expands 

 and then gradually tapers to the base. Apical whorl highly polished, 

 bluntly rounded and partly concealed by callus. Last two whorls 

 more inflated than the preceding and provided with a prominent, 

 rounded, subsutural spiral band below which the shoulder is orna- 

 mented with short, rounded axials or folds. Aperture about three- 

 fourths length of shell, medially a little wider, deeply notched poste- 

 riorly, and expanded at the anterior canal. Outer lip with a strong 

 Avell-defined varix, ornamented within but not exending beyond the 

 varix or over the posterior one-fifth of the margin, Avith 18 denticu- 

 lations; pillar concave and provided with four grooved plates — the 

 posterior two are nearly transverse and the anterior two oblique ; the 

 anterior one forms the margin of the canal and is continuous with 

 the outer lip varix. 



Dimensions: Figured specimen (U. S. Nat. Mus. Cat. No. 352656) 

 measures: Length 13.6 mm.; greatest diameter 6.5 mm.; length of 

 aperture, 9 mm. 



The species resembles M. soioerhyl Gabb, a species occurring 

 in "both the Cercado and Gurabo formations of the Dominican Re- 

 public, but it differs from this species in being a more slender shell 

 and possessing short axials at the shoulder of the spire below the 

 suture. 



Locality of figured specimen : 9219. Guaico-Tamana Road. 2 chains 

 east of mile 13 from junction with Eastern Main Road. 



Occurrence. — Middle or lower Miocene : 9212, 1 mile south of 

 Brasso. 



MARGINELLA SPRINGVALENSIS Maury 



Plate 6, fig. 13 



Marginella spring valen^is Maury, Bull. Amer. Paleont., vol. 10, no. 42, p. 200, 

 pi. 34, figs. 10, 14, 1925. 



Shell large, ovate, solid, and probably polished (surface cor- 

 roded), and about four whorled. Spire acuminate and extending 

 5 mm. above outer lip; body whorl strongly and roundly inflated 

 at the posterior tliird, and in front provided with a moderately thick 

 v.'ash of callus. Aperture 2 mm. wide above and 6 mm. below; otiter 

 \\\) slightly arcuate, outer margin with a wide and strong varix, 

 inner margin smooth. Columella concave, provided with four equal • 

 sized plications — anterior two are closer-set and more oblique. The 

 lower extremity of the aperture is broken away. 



