NAPLES FAUNA IN WESTERN NEW YORK, PART 2 287 



ones in front. These are of precisely the same character as the posterior 

 plications in Lunulicardium and may also be compared to those of Euthy- 

 desma. Beushausen has shown that the German forms of the species do 

 not always carry concentric undulations, but it is evident from our specimen 

 that the sharply defined and distinct concentric lines of the body of the 

 shell rise on low rounded surfaces, while about the periphery the lines are 

 more closely crowded and less elevated. Though this is the only specimen 

 observed which in our judgment can be referred to O. c o n c e n t r i c a, it 

 seems to us probable that the shell termed by Williams L u c i n a 

 wyomingensis (oft. cit?) is of the same nature, the figures indicating 

 the umbonal radii. This species does not enter the Naples subprovince, 

 and likewise, as we have before observed, the O. suborbicularis 

 occurs rarely in the Chautauqua subprovince. 



Dimensions. The specimen before us is a left valve measuring in 

 hight and length 20 mm. 



Habitat. Genesee province ; Chautauqua subprovince. Correll's 

 point, near Brocton, Chautauqua co. Lucina wyomingensis is from 

 Varysburg, Wyoming co. 



Ontaria pontiaca sp. nov. 



Plate 8, fig. 21 



Shell suborbicular or slightly transverse. Hinge line straight, extend- 

 ing two thirds the length of the shell ; divided subcentrally by the beak, 

 which projects slightly beyond it ; beaks deflected very slightly anteriorly. 

 Cardinal area narrow, erect. Valves subequilateral. Umbo gently and 

 regularly convex, sloping with convex curve to the basal margin, but the 

 surface is concave both in front and behind the umbo on the slope of the 

 lateral margins. Marginal curve quite regular, the surface somewhat more 

 expanded behind than in front. Marginal surface somewhat abruptly 

 deflected. 



Surface smooth, showing no cardinal or other radial plications and only 

 vague, obscure suggestions of concentric lines. This general smoothness 

 of the surface is indicated by a number of individuals and serves, with 



