150 PALEONTOLOGY OF ILLINOIS. 



Position and locality: Roof of the middle coal seam, LaSalle, 

 Illinois. 



Collector, A. H. Worthen. 

 No. 2486 of the Illinois State Museum. 



GENUS GONIATITES. DeHaan. 



GONIATITES MONROENSIS. (sp. nOV.) 

 PL XXVI. Fig. 5. 



Shell of medium size, discoid, compressed, whorls about four, 

 contiguous, sides slightly rounded, but narrowly rounded on the 

 dorsum. 



Lateral diameter of the whorls, slightly less than the dorso- 

 ventral at the middle of the last volution ; width of the umbilicus 

 equal to about once and a half that of the dorso-ventral diame- 

 ter. The lower margins of the volutions are sharply rounded 

 into the umbilicus. 



Septa composed of two rounded lobes on each side with an 

 obtusely pointed projection between them. Surface smooth. 



Greatest diameter 1% inches; lateral diameter of outer whorl 

 % inch; dorso-ventral diameter near the aperture 9 / 16 inch. 



Locality and position : This species is represented by a single 

 specimen only, which was obtained from a thin bed of partly 

 brecciated limestone that forms the upper part of the St. Louis 

 limestone near Waterloo, Monroe county, Ills. 



Collector, A. H. Worthen. 



No. 2589 of the Illinois State Museum. 



GENUS SOLENOCHEILUS, Meek and Worthen. 



SOLENOCHEILUS INDIANENSE. (sp. nOV). 

 PI. XXVIII, Figs. 1-la. 



Shell moderately large, sub-globose in form; umbilicus deep 

 and about two-thirds as wide as the dorso-ventral diameter; 

 test thin and without ornamentation. 



Septa comparatively wide, two and a half equaling in width 

 the dorso-ventral diameter, the outer ones curving gently for- 

 ward on the dorsal portion of the shell. 



