1 



176 PALEONTOLOGY. 



within ; columella provided with one rather strong oblique fold below, and 

 a much smaller less oblique one about half-way up the aperture. 



Length, about 0.77 inch; breadth, 0.50 inch; apical angle nearly regu- 

 lar, divergence about 80°. 



I know of no other shell so nearly allied to this as to render a com- 

 parison necessary. Its most striking character is the presence of the little 

 folds around the upper part of its body-volution and on those of the spire. 

 These Avill at once distinguish it from any type of the Melampince known to 

 me, even in specimens not in a condition to show any of the other char- 

 acters. 



Locality and position. — The only three specimens of this species I have 

 seen were found by Colonel Simpson's party in the brackish- water carbon- 

 aceous beds at the mouth of Sulphur Creek, on Bear River, Utah. 



OEEIPHASIIDy^iE. 



Pyrgulifera humerosa, Meek.* 



Plate 17, figs. 19, 19 a, and wood-cut fig. 6. 



Melania humerosa, Meek (1860), Proceed. Acad. Nat. Sci., XII, 313. 



Tiara humerosa, Meek (1866), in Conrad's Smithsonian Check-List of Eocene and Oligo- 



cene Fossils, 12. 

 PyrguUfera humerosa, Meek (1872), in Dr. Hayden's Second Ann. Eeport Geol. Survey 



of the Territories, 294 and 299 ; and (1876) in Col. Simpson's Eeport Expl. 



across the Great Basin of Utah, 363, i)l. v, fig. 6 a, h, c. 



Shell attaining a rather large size, moderately^ solid, ovate-subfusiform; 

 spire prominent, distinctly turreted; volutions five and half to about seven, 



*This genus is related to Lithasia, as originally defined by Professor Haldemau, 

 and presents the following characters : 



Shell subovate, thick, imperforate ; spire produced, turreted ; volutions angular, 

 shouldered, and nodular above ; surface typically with vertical ridges and revolving 

 markings; aperture subovate, faintly sinuous, but not notched or distinctly angular 

 below ; outer lip prominent in outline below the middle, retreating at the base, and 

 subsinuous at the termination of the shoulder of the body- volution above; peristome 

 continuous; inner lip a little callous below, and thickened all the way up, but without 

 a protuberant callus above, sometimes with a shallow umbilical furrow along its outer 

 margin below. 



Differs from Lithasia, Haldeman, in not having its aperture distinctly angular 

 and notched, or subcanaliculate below, in wanting a protuberance at the top of the 

 inner lip, and in having a more produced, distinctly turreted spire, as well as very 

 different surface markings. 



