PALAEONTOLOGY OF IOWA. 719 



SURFACE very finely striated in the direction of the lines 

 of growth. 



Fig. 8. View of specimen (natural size), showing the entire spire and a portion of 

 . the columellar lip. 



Geological formation and locality. In the Lower Coal measures : Des- 

 moines valley, Iowa. 



Macrocheilus newberryi. 



PLATE XXIX. FIG. 9. 



Loxonema newberryi & L. carinata : STEVENS in Silliman's American Journal of Science, 



Vol. 25, New series, 1858, p. 259. 



SHELL subfusiform, symmetrically conical above the last 

 volution. Volutions about eight, the last one moderately 

 ventricose and longer than the spire above. Suture -line 

 slightly concave, and marked by a narrow fillet : aperture 

 elongate, not much inflated ; columellar lip thickened below, 

 with a defined spiral groove above the callosity, which is 

 distinct within the aperture, and becomes obsolete on the 

 exterior shell. 



SURFACE markings obscure. 



The shell is replaced by iron pyrites, and the surface markings are indistinct. 

 Possibly the narrow spiral band marking the sutures is simply due to the solution 

 and removal of a portion of the shell on each side of the suture-line. 



On comparing the original specimens of the two species described by Dr. STEVENS, 

 with the one here figured and described, I am not able to find the means of specific 

 distinction. 



Fig. 9. View of the anterior side of the shell, natural size. 



Geological formation and locality. In the Coal measures of Illinois. 

 ( From Dr. R. P. STEVENS.) 



Macrocheilns paludingeformis ( n. s.). 



PLATE XXIX. FIG. 10. 



SHELL thin, ovoid-acute ; the last volution ventricose, a 

 little longer than the spire above : spire somewhat rapidly 

 tapering. Volutions about eight, the upper ones very mode- 

 rately convex. Suture-line plain, very slightly impressed : 

 aperture undetermined. 



