IDESCI^IiFTIOISrS OIP IFOSSILS. 



SILURIAN SPECIES. 



MOLLUSCA. 

 GASTEROPODA. 



solariidj:. 



? Genus OPHILETA, Vamixeni. 



OPniLKTA COMPLANATA, rar. NANA. 

 Plate 1, figs. 1, I a, lb. 



OpMJeta complanaia, Vanuxera (1842), Report Third Geol. Dist. N. Y., 36, fig. 2— 

 Hall (1847), Palaeont. N. Y., I, pi. ii, fig. 2, and pi. iii, fig. 6. 



Ophileta complanata var. nana, Meek (1870), Eai den's Prelim. Report of the U. S. Geol. 

 Survey of the Territories, 295. 



Shell compressed-planorbicular, both sides slightly concave ; volutions 

 about six, very narrow, and increasing very gradually in size, flattened and 

 slightly oblique on the.outer side, and presenting a quadrangular transverse 

 section, with upper and lower surfaces somewhat converging inward from 

 the angle on each side of the periphery. 



Greatest diameter, 0.30 inch ; thickness or height, 0.06 inch ; diameter 

 of last volution, measuring in the direction of the plane of the shell, 

 0.05 inch. 



As Vanuxem's species was not fully described or well figured, it is 

 scarcely possible to be positively sure that our shell might not be only a 

 closely-allied species, without direct comparison with authentic examples 



