31 



This shell bears a close resemblance to Littorina pusilla of 

 Mc Coy, Carb. fos. Ireland, p. 32, pi. v. fig. 26. 



^"'Natica Carlyana. — Shell sub-globose ; spire short, con- 

 sisting of about three volutions, which increase very rap- 

 idly, the last one extremely ventricose; suture not distinctly 

 defined ; aperture ovate, straight on the columellar side ; 

 outer lip sharp ; inner lip thickened ; columella with a 

 distinct groove near the base of the lip for the reception of 

 the operculum ; surface marked by fine elevated striae cor- 

 responding to the lines of growth. 



Height -10 to '30 ; diameter 'OS to *34 of an inch. 



Locality. — Spergen Hill and Bloomington, la. ; Alton, 111. 



CAPULUS, Montfort. 



v/(5apulus acutirostris. — Shell obliquely conical, more ab- 

 ruptly contracted above, and continued in more slender 

 proportions to the apex, which is incurved, making about 

 a single volution without contact with the body of the shell ; 

 aperture sub-circular, margin sinuate ; surface sub-plicate, 

 with narrow sub-angular folds and wider depressed spaces ; 

 lines of growth strong, abrupt upon the angles and arching 

 forwards on the spaces between. 



Locality. — Spergen Hill and Bloomington, la. 



BELLEROPHON, Montfort. 



i Bellerophon cancellated. — Shell sub-globose; aper- 

 ture transversely oval, arcuate, with the lip reflexed at the 

 sides ; umbilicus small in young shells, and scarcely visible 

 in the older specimens from the thickening of the lip ; sur- 

 face marked by fine longitudinal elevated striae, of which 

 about thirty may be counted on each side of the carina, in- 

 creasing by implantation with the age of the shell ; carina 

 rather narrow and little elevated, very indistinctly marked 

 by the longitudinal striae. Transverse striae in the direction 

 of the lines of growth, irregular, subimbricate, more dis- 



