INVERTEBRATES. 



DESCRIPTIONS OF SOME NEW SPECIES OF FOSSIL SHELLS 



FKOM THE 



LOWER CARBONIFEROUS LIMESTONES 



COAL MEASURES OF ILLINOIS.' 



By A. H. WOETHEN. 



OETHOCEEAS ILLINOIENSIS, Sp. nov. 



Shell of medium size, gradually enlarging from the apex; section 

 slightly ovate, siphuncle rather large, and placed near the margin 

 of the shell. 



Septa moderately convex and oblique to the axis, being arched 

 strongly upward about twice their width on the siphuncular side, 

 and equaling in width about one-fifth of the shortest diameter of the 

 shell. Surface markings unknown. 



Length of the largest specimen seen, about 6 inches; greatest 

 diameter of the outer chamber, 2 inches; greatest width at the 

 apex, | inch. 



This rare shell is only known from three imperfect specimens ob- 

 tained from the upper limestone at Chester. 



No. 2,484, of the Illinois State collection. 



cases of the Museum, where they will be accessible to those who may desire to compai o 

 them with similar forms from other localities. 



