

416 NEW YORK STATE MUSEUM 



PLATE 12 



Genus posidonia Bronn 



Page 264 



Posidonia mesacostalis Williams (sp.) 



Page 267 



i A left valve. X3 

 2 A right valve. X3 

 3-6 Left valves. X3 



Chautauqua subprovince 



Johnson's falls, near Strykersville, Wyoming county 



7 A right valve, X3, with highly developed ear 



8 External cast of right valve with the opposite valve over- 



lying. X3 



9 A left valve. X3 



Chautauqua subprovince Big Sister creek, Angola 



Posidonia attica Williams (sp.) 



Page 265 



10, 11 Right and left valves of the same individual. X3 

 1 2 A right valve. X5 



Naples subprovince Pogue's hill, Dansville 



13 A right valve. X5 



Chautauqua subprovince Big Sister creek, Angola 



14 A right valve. X3 



15 Enlargement of a portion of the surface. X5 



Naples subprovince Pogue's hill, Dansville 



Posidonia venusta Minister var. nitidula var. nov. 



Page 26B 



16, 17 Right valves. X2 



18 The two valves in juxtaposition. X3 



19 A right valve. X3 



Chautauqua subprovince 



16, 17, 19 Correll's point, Lake Erie; 18, Gowanda 



