JDZESCE^IIPTIOnsrS oif ihossils. 



SILURIAN SPECIES. 



MOLLUSOA. 



GASTEROPODA. 



SOLARIIDJ]. 

 ? Genus OPHILETA, Vanuxem. 

 Ophileta complanata, var. nana. 



Plate ] , figs. 1, 1 a, 1 &. 



Ophileta complanata, Vanuxem (1842), Keport 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), Hayden's Prelim. Report of the U. S. Geol. 

 Survey of the Territories, 295. 



Shell compressed-planorbicular, both sides slightly concave ; volutions 

 about six, very narrov^^, and increasing very gradually in size, flattened and 

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

 section, vrith 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 



17 



2pr 



y 



