500 PALAEONTOLOGY OF ILLINOIS. 



FORAMINIFERA ? 



Genus EEOEPTACULITES, Defrance. 

 Eeceptaculites forzuostjs, M. and W. 



PI. 24, Kg. 1. 

 Eeceptaculites formoaus, ilEEK and Wortiien, 1870. Proceedings Acad. Nat. Sci., Philad., p. 23. 



Body obovate, the breadth beiDg about three-fourths the bight, aud 

 the widest point a little above the middle; upper end rounded and 

 without any umbilicoid concavity or opening, unless it may be a very 

 small one; sides gradually tapering with a slight convexity from a 

 little above the middle to an apparently moderate sized base of attach- 

 ment. Cell openings or depressions shallow, quadrangular, or trans- 

 versely rhombic (those on the upper part wider than high), arranged in 

 spirally ascending rows, which make nearly one turn in passing from 

 the base to the center of the top; each with a transverse linear central 

 furrow, from which a similar furrow passes to the lower angle ; central 

 perforations of the cell depressions minute, and generally closed in the 

 typical specimen. 



Hight 1.75 inch ; breadth 1.22 inch. 



This species differs from all others known to us, especially from any 

 Upper Silurian horizon, in its elongated, obovate form, its outline being 

 almost exactly obovate, excepting the truncation of the lower (smaller) 

 end. In general appearance it perhaps most nearly agrees with a form 

 found in the Galena limestone, and referred by us doubtfully to B. glob- 

 ularis, Hall, in the third Vol. 111. Geol. Eeports, PI. 2, fig. 2 a, b. It 

 differs, however, from that species in having the upper end more round, 

 or less depressed, and'without any umbilicoid impression. Its cell impres- 

 sions are also very different, not being near so crowded, and instead of 

 becoming more crowded and narrower on the lower half, they are less so 

 there than above ; while the central perforation of each is smaller. 



Position and locality : Bridgeport, Cook county, Illinois. Niagara 

 Group. Upper Silurian. 



