FOSSILS OF THE COAL MEASURES. 597 



wanting; columella a little arched and twisted; surface 

 showing- only very faint traces of lines of growth. 



Length, about 0.55 inch; breadth, 0.23 inch; apical angle 

 with convex slopes, divergence about 40 deg. 



Tliis species has nearly the form of Ijoxonema Xcicbcrryi, of Stevens, 

 (an elongated Mdclrrocheilu*,) but it is much smaller, ami wants the 

 characteristic fold on the columella seen in that shell. In size it agrees 

 more nearly with our Polypfomoprii in<n-nata, from the upper part of 

 the Coal Measures at Springfield, Illinois. It has the body volutiou 

 more produced below, however, and without any tendency to form an 

 obtuse angle around the middle, while the slopes of its spire are more 

 convex in outline, owing to the proportionally larger size of the middle 

 whorls. This latter character gives it the chrysalis- like form that sug- 

 gested the specific name. 



Locality and position Hodge's creek, Macoupin county, Illinois; from 

 the lower part of the Coal Measures. 



Genus AXOMPHALUS, M. and W. 



ANOMPHAUS ROTULUS, M. and \T. 



PI. 29, Fig. 10. 

 Anomphalits rotuhu, MEEK anil WOKTHEN, It66. Proceed. Acad. Xat. Sci.. Phila., p. 268. 



SHELL small, depressed, narrowly rounded on the peri- 

 phery ; spire scarcely visible above the body whorl in a side 

 view; volutions three and a half to four, increasing rather 

 rapidly in breadth, last one sloping with a moderate con- 

 vexity between the suture and the periphery, and slightly 

 excavated in the umbilical region ; suture not impressed ; 

 aperture transversely suboval, being rounded on the outer 

 side, and straightened on the lower half of the inner side, 

 but modified by the convexity of the body whorl above ; 

 surface showing scarcely any traces of lines of growth, 

 even under a good magnifier. 



Breadth of a large specimen, 0.19 inch; hight, 0.07 inch. 



Position and locality Hodge's creek, Macoupin county, Illinois ; lower 

 division of Coal Measures. 



