PALEONTOLOGY OF IOWA. 723 



UPPER surface marked by strong elevated striae, which, 

 from the inner side of the volution, curve very gently back- 

 wards, and then slightly advance towards the periphery, 

 where they become more conspicuous, rising over the carinae 

 somewhat in irregular fascicles, and giving a seminodulose 

 charactar to this part of the shell : striae vertical on the 

 periphery, stronger on the carinated margin below, and again 

 less conspicuous in the umbilicus than on the upper side of 

 the shell. Cast smooth. 



This species may be identical with the one cited above; but the description of 

 " back obtusely carinated in the middle", does not apply to the shell under exami- 

 nation. 



Fig. 14 a. View of the lower side and umbilicus. 



Fig. 14 b. Dorsal view, showing the aperture. 



Fig. 14 c. View of the upper side, showing the depressed spire. 



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



Belleroplion nodocarinatus ( n. s.). 



PLATE XXIX. FIG. 15 a, b, c. 



SHELL subglobose, expanded at the sides, without umbili- 

 cus. Back and sides of the shell, near the aperture, marked 

 by longitudinal or revolving ridges or carinae, about seven 

 or eight on each side of the centre ; the two central ones of 

 which, in their extension forward, become more prominent, 

 and form a kind of double carina which becomes nodose to- 

 wards the aperture : a broadly concave depression on each 

 side of the carina where the shell is thinner, becoming 

 convex and extremely thickened towards the margins. 



The aperture is imperfect in the specimen examined. The species bears a general 

 resemblance to B. urii of Europe; but the carinae are much fewer and coarser, while 

 the double nodose central carination is a very distinctive feature. 



Fig. 15 a. View of the imperfect aperture and back of the shell. 

 Fig. 15 b. Lateral view of the same. 



Fig. 15 c. Dorsal view, showing the double dorsal carina, which becomes nodose 

 towards the aperture. 



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

 Iowa. 



