18 BULLETIN NO. 2. 



Position and locality: Oolitic beds of the St. Louis group, 

 Monroe county, 111. 

 No. 2523 of the Illinois State collection. 

 Collector, A. H. Worthen. 



GENUS EDMONDIA, DeKoninck. 



EDMONDIA VARSOVIENSIS. (sp. nOV.) 



Shell above the medium size, compressed and evenly rounded 

 at the extremities ; length about one-third greater than the height ; 

 basal margin broadly semi-ovate in outline, dorsal margin sloping 

 abruptly from the beaks in front, and nearly straight behind for 

 about two-thirds the entire length of the shell, and thence round- 

 ing into the posterior margin ; beaks depressed and located near 

 the anterior extremity. 



The surface of the cast shows traces of deHcate closely arranged 

 concentric striae, and a few more distinct lines of growth. 



Length of the typical specimen 2| inches ; height If inches. 

 This shell is only known from limestone casts. 



Position and locality : From the upper part of the Keokuk 

 limestone, Warsaw, 111. 



No. 2502 of the Illinois State collection. 



Collector, A. H. Worthen. 



EDMONDIA ILLINOIENSIS. (sp. DOV.) 



Shell of medium size, transversely sub-oval, convex, broadly 

 rounded at the extremities ; dorsal margin straight behind the 

 beak for about two-thirds its length, and thence rounding into the 

 posterior border; basal margin slightly sub-ovate ; beak depressed 

 and located about one-third the entire length of the shell from 

 the anterior extremity. Surface of the cast marked by distinct 

 parallel lines of growth. 



Length 1^ inches; height ly'^- inches; convexity of the valves 

 about yV inch. 



This is a smaller and more convex shell than the preceding 

 species, and shows none of the fine concentric striae that appear 

 on the E. Varsoviensis. 



Position and locality : Same as the preceding species. 



No. 2503 of the Illinois State collection. 



Collector, A. H. Worthen. 



GENUS AVICULOPECTEN, McCoy. 



AVICULOPECTEN ORESTES, (sp. nOV.) 



Shell below the medium size, equilateral, broadly ovaie wben 

 divested of the ears; hinge line about equal to the greatest breadth 

 of the shell ; ears of moderate size and smooth or showing only 



