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PROCEEDINGS OF THE ACADEMY OP 



This species has nearly the form of Loxonema Newberry!., of Stevens (an 

 elongated Macrocfie : lus), but is much smaller, and wants the characteristic 

 thickening and fold of the columella seen in that species. In size it agrees 

 more nearly with our Polyphemopsis inornata, frnm a higher position in the 

 coal-measures at Springfield, Illinois. It has its body volution more produced 

 below, and less disposed to become subangular 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 suggested the specific name. 



Locality an'dposltion.=H.o&ge's Creek, Macoupen County, 111. Lower Coal- 

 Measures. 



Naticopsis Littonana, var. genevievensis. 



Natica Littonana, Hall, 1856. Trans. Abany Inst., vol. iv. (p. 30, of 

 extract.) 



The shell we here place provisionally as a variety of Natica Littonana, 

 Hall (a true Naticopsis), agrees almost exactly with authentic examples of 

 that species from the original locality, excepting that it attains some six or 

 eight times the size of the largest of the Indiana specimens, and yet has the 

 same number (four) of whorls. Some of the specimens have the oblique 

 lines rather more distinctly defined around the upper side of the body whorl 

 than we have seen on any of the typical examples of Naticopsis Lit- 

 tonana, but tli is might be expected from their much larger size. These lines, 

 however, are quite distinct on some of the unworn specimens of N. Littonana, 

 from Spergen Hill. 



Our specimens of the shell under consideration show the inner lip to be 

 little thickened and very smooth, while the columella is moderately flattened. 

 The surface is quite smooth up to the area below the suture, marked by the 

 oblique, very regular stria?, which terminate very regularly and abruptly at 

 their outer extremities. In worn specimens these lines, however, are entirely 

 obsolete. It is not impossible that this may prove to be a distinct species 

 from the N. Liltununa, though we here place it provisionally as a variety 

 of that species. 



Length, 0-73 inch ; breadth, 0'67 inch ; apical angle about 115. 



Locality and position. St. Genevieve County, Missouri, and Randolph 

 County, Illinois, Chester division of the Subcarboniferous series. 



Genus ANOMPHALUS, M. & W. 



Shell depressed, sublenticular, imperforate, smooth and without a spiral band ; 

 volutions somewhat embracing above, and each hiding all the preceding ones 

 below ; aperture wider thau high ; peristome not continuous ; labium simple 

 and without a notch or sinus, projecting forward above ; labium a little sinu- 

 ous and slightly spreading in the more or less impressed umbilical region. 



The type for which this genus is proposed is a little shell having somewhat 

 the aspect of a Rotella, but wanting the callus seen filling the umbilical im- 

 pression in that genus. At a first glance it might be mistaken for a small 

 Straparollus, but on examining the underside it is seen to be entirely without 

 an umbilicus, though slightly impressed in the middle ; while its lip continues 

 in below nearly to the centre, where it is abruptly deflected upwards, becomes 

 a little thickened, somewhat spreading and more or less sinuous, much as we 

 see on each side of some species of Bellerophon. 



We have little doubt but this genus belongs to the Rotellidoe, which was 

 certainly represented during the deposition of the palaeozoic rocks, apparently 

 even by the typical genus Rote/la, the well known Devoniau Ilelicites helicuii- 

 J'ormis of Schlotheim being apparently a true Rotella. 



Anomphalus kotulus, M. & W. 

 Shell small, depressed, sublenticular, narrowly rounded ou the periphery ; 



[July, 



