CARBONIFEROUS FOSSILS. 15 



GASTEROPODA, 



Genus EUOMPHALUS, Sowerby. == STRAPAROLLUS, 



Montfort ? 



Subgenus OMPHALOTROCIIUS, Meek. 



Euomphalus "Whitneyi, Meek. 



PL 2, Fig. 8, and 8 a. 



Shell large, rather thick, depressed-subtrocliiform, widely am- 

 bilicatcd. Umbilicus deep and conical, nearly or quite equalling 

 the breadth of the last whorl at the aperture. Volutions four to 

 four and a half, sloping and concave above, and bicarinate around 

 the outer side, the carinse being separated by a wide, nearly ver- 

 tical, flattened or concave space. Between the lower carina and 

 the obtusely subangular margin of the umbilicus the under side 

 of the whorls is nearly flat, or slightly convex ; while the side 

 forming the walls of the umbilicus is more or less flattened and 

 very abrupt. Suture linear, but well defined. Aperture subor- 

 bicular, or transversely suboval, not modified by the preceding 

 turn. Lip rather obtuse, and a little concave in outline on the 

 inner side; while on the under side (judging from the curve of 

 the lines of growth) it is oblique, and more or less sigmoid in out- 

 line. The same obliquity continues around the outer and upper 

 sides, so that the margin of the lip must project forward con- 

 siderably farther above than below. Surface marked only with 

 lines of growth, which are most strongly defined on the under 

 side and within the umbilicus. 



Greatest breadth about 4.60 inches; height near 2 inches. 



All the specimens of this shell in the collection are imperfect, but, taken to- 

 gether, they convey a correct idea of its form and most of its characters. Its 

 biangular, broadly flattened periphery, and general outline, give it so much the 



