384 PALAEONTOLOGY OF ILLINOIS. 



appear to indicate affinities to Macrocheilus and Polyphemopsis ; but the posses- 

 sion of a distinct canal, and straight columella, remove it widely from these 

 genera. Macrocheilus limnseiformis, of McCoy, and M. elongatus, of Phillips, 

 should doubtless be ranged in the same group with our shell. 



Soleniscus typicus, M. and W. 



PI. 31, figs. 15a, 156. 



Soleniscus typicus, Meek and Worthen, October, 1860. Proceed. Acad: Nat. Sci., 

 Philad'., p. 467. 



Shell fusiform ; spire rather elevated, and acutely conical ; 

 volutions seven to seven and a half, flat or but slightly convex, 

 increasing rather rapidly in size, last one forming more than 

 three-fourths the entire length, somewhat ventricose in the 

 middle, and contracting rather gradually into the straight 

 canal below; suture somewhat shallow; aperture very narrow, 

 or lanceolate, acutely angular above, and narrowing gradually 

 into the canal below; outer lip sharp; fold of the columella 

 located a little below the middle of the aperture. Surface 

 smooth or only showing very obscure traces of lines of growth. 

 Length, 0.73 inch; breadth, 0.30 inch; apical angle slightly 

 concave, divergence 40°. Length of aperture and canal, about 

 0.34 inch ; breadth of former, 0.11 inch. 



This interesting shell is more nearly like Macrocheilus limnseiformis, McCoy 

 {Brit. Palaeozoic Fossils, pi. 3, i, fig. 40), than any other species with which we 

 are acquainted, but is smaller, and much less ventricose around the middle of 

 the body whorl. The resemblance is so striking, however, that we have little 

 hesitation in referring Prof. McCoy's species to our genus. 



Locality and position : Upper Coal Measures, Springfield, Illinois. 



