102 PALEONTOLOGY OF ILLINOIS. 



BRACHIOPODA. 



GENUS DISCINA. Lamarck. 

 DISCINA VARSOVIENSIS. Worthen. 



PL XI, Fig. 7. 



Discina varsoviensis, Worthen, March, 1884. Bulletin No. 2 of the Illinois State Mu- 

 seum of Natural History, page 23. 



Shell of medium size, ovate in outline, anterior and posterior 

 margins nearly equal in width. The larger or free valve is 

 crushed so that its general form cannot be clearly determined; 

 its surface, however, is ornamented around the borders with ten 

 to twelve or more rather strong and sharp concentric ridges, 

 which become less conspicuous or obsolete towards the apex. 



The lower valve is nearly flat and marked around the border 

 by fine concentric ridges rather less conspicuous than those on 

 the other valve, with a long narrow slit or foramen extending 

 from about the center of the valve more than half way to the 

 posterior extremity, and surrounded by an elevated margin. 



Length of an average size lower valve % inch; greatest breadth 

 of the same 10 / 16 inch. 



Position and locality: Keo'kuk limestone, Warsaw, 111. 



Collector, A. H. Worthen. 



No. 2545 of the Illinois State Museum. 



GENUS TEREBRATULA. Llwyd. 

 TEREBRATULA ROWLEYI. Worthen. 



PL XI, Figs. 6,6a,6b. 



Terebratula rowleyi. Worthen, March. 1884. Bulletin No. 2 of the Illinois State Museum 

 of Natural History, page 23. 



Shell below the medium size, iuequivalve, conical; ventral valve 

 strongly convex in the middle from the beak to the basal mar- 

 gin, and rapidly sloping on either side to the lateral borders. 



