20 



cross the revolving carinse in sigmoid flexures and crenulate the 

 carinse so as to beautifully ornament the shell. The crenulations 

 are hardly visible to the naked eye but are very distinct under an 

 ordinary magnifier. 



This species so far as disclosed, by our specimen, is a Cyclo- 

 nema, possibly, the aperture may be different from a typical 

 species, but we have no doubt, at present, of the generic refer- 

 ence. It is widely separated, however, by its general form and 

 surface ornamentation from all other described species, and no 

 comparison is necessary to distinguish it. 



Found by Geo. K. Greene, in the Knobston Group, near New 

 Albany, Indiana, and now in the collection of Wm. F. E. Gurley. 



Family EUOMPHALHXE. 



STRAPAROLLUS MISSOURIENS1S, n. sp. 



Plate II, Fig. 35, a specimen preserving the central whorls; Fig. 

 36, a large specimen, with central whorls broken. 



Shell discoid; below medium size. Spire below the plane of 

 succeeding volutions. Volutions five or six, lying in the same 

 plane, slender and very slowly expanding. Transverse section of 

 a whorl nearly circular, but probably slightly ovate with the nar- 

 rower end on the inside of the volutions. The inner whorls ap- 

 pear to be round, but a subovate form is assumed as the aper- 

 ture is approached. Aperture not preserved, in any of our speci- 

 mens. None of the specimens collected exceed an inch in diame- 

 ter. The surface is generally smooth, but the better preserved 

 specimens show very fine transverse lines, under an ordinary 

 magnifier. 



We have numerous fragments of this species and some of them 

 preserve the shell in excellent condition, with five transverse lines 

 resembling those common on Spirorbis. The inner whorls might 

 very readily be mistaken for a Spirorbis. It resembles S. cly- 

 menioides, from the Upper Helderberg Group, more than any 

 other species known to the authors. It is distinguished by the 

 more slender whorls, nearer circular transverse sections and sur- 

 face ornamentation. It is also a smaller species. 



Found by R. A. Blair, in the Chouteau limestone, at Sedalia, 

 Missouri, and now in the collection of S. A. Miller. 



