INVEETEBEATES. 825 



Greatest width of the specimen in hand, 4f inches; height of 

 the outer whorl, 1^ inches. 



Position and locality : The only specimen seen was obtained at 

 Montezuma, Pike county, Illinois, from near the base of the Bur- 

 lington limestone. 



No. 2,487, of the Illinois State collection. 



DENTALIUM ILLINOIENSIS, Sp. nov. 



Shell above the medium size, long, straight cylindrical, slightly 

 tapering, and scarcely inflated at the aperture. Surface originally 

 smooth, but slightly roughened from weathering in the specimen 

 under examination. 



Length, 5| inches ; width near the aperture, 7-16 in. 



This species differs from D. Missouriense of Swallow, in its larger 

 size, smooth surface and straight form. 



Position and locality : Lowest beds of the Chester limestone, Ches- 

 ter, Illinois. 



No, 2,488, of the Illinois State collection. 



CONULARIA CHESTERENSIS, Sp. nov. 



Shell attaining a medium size, long and rather slender, gradually 

 tapering, nearly equally four sided, the four angles being distinctly 

 and rather deeply furrowed, while a slight furrow marks the median 

 line on each side. The sides are crossed by numerous raised costse, 

 which arch slightly forward from the angles to the median line, 

 making an angle with that line of about 14. They do not cross 

 the angular furrows, but are alternately arranged so that those on 

 one side terminate at the intervening space between those on the 

 opposite side. These spaces are about twice as wide as the costse, 

 and are widest at the median line. 



The aperture is not well preserved in any of our specimens, but 

 the shell was notched at the angles and probably contracted at the 

 aperture. 



Length of a rather large individual, o inches ; breadth between 

 the angles near the aperture, 1 inch ; number of costse in the space 

 of an inch near the aperture, 20; near the apex, 80. 



Position and locality: Chester limestone, Chester, Illinois. 



No. 2,489, of the Illinois State collection. 



