CARBONIFEROUS FOSSILS. 15 



GASTEROPODA, 



GENUS EUOMPHALUS, Sowerby. = STRAPAROLLUS, 



Montfort? 



SUBGENUS OMPHALOTROCHUS, Meek. 

 EUOMPHALUS WHITNEYI, Meek. 



PI. 2, Fig. 8, and 8 a. 



SHELL large, rather thick, depressed-sub trochifornij widely um- 

 bilicated. 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 co'nvex ; 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 



