466 PROCEEDINGS OF THE ACADEMY OF 



conical, rather attenuate, and acutely pointed above ; volutions eight to eight 

 and a half, convex, and increasing rather gradually in size, last one moderately 

 large, somewhat contracted, and extended below; suture well defined, espe- 

 cially between the lower whorls ; aperture narrow, subovate, a little oblique, 

 acutely angular above, rather narrow, and terminating in a small rounded 

 sinus at the base of the columella below, less than half the length of the entire 

 shell ; outer lip thin and sharp, with a scarcely sigmoidal margin ; columella 

 arcuate, and somewhat twisted below ; surface smooth, but showing under a 

 lens very fine, obscure lines of growth. 



Length, 1-10 inch; breadth, 0-43 inch; apical angle regular, divergence 

 30. Length of aperture, 0-47 inch ; breadth, 0-20 inch. 



Locality and position. Springfield, Illinois. Upper Coal Measures. 



Genus EULIMA, Risso. 



Eulima? peracuta. Shell comparatively large, elongate, conical; spire 

 much elevated, attenuate, very acutely pointed at the apex, and sometimes 

 subulate. Whorls about thirteen, nearly or quite flat, and increasing very 

 gradually in size ; last one forming a little more than one-third the entire 

 length, slightly prominent around the middle, somewhat extended below .; 

 suture moderately distinct, particularly between the lower whorls. Aperture 

 rather narrow, subovate, acutely angular above, and narrowly rounded below ; 

 outer lip thin and sharp ; inner lip very slightly thickened, and a little re- 

 flexed below ; columella arcuate or faintly sinuous. Surface polished, but 

 showing under a good lens extremely fine, very obscure lines of growth. 



Length, 1-67 inch; breadth, 0-54 inch; apical angle regular, divergence 

 22. Length of aperture, 0-55 inch ; breadth of do., 0-30 inch. 



Locality and position. Jacksburg, St. Clair county, Illinois. Lower Coal 

 Measures ; also near Springfield, in Upper Coal Measures. 



Genus MACROCHEILUS, Phillips. 



Some confusion exists in regard to the limits of this genus, in consequence 

 of the fact that Prof. Phillips did not define it clearly, and unfortunately in- 

 cluded in it species belonging to several groups, without designating what 

 particular species he regarded as the type of his genus. Nearly all subsequent 

 authors, however, agree in referring to it those oval, or subglobose forms, with 

 a thickened inner lip, and a more or less developed fold on the columella, 

 such as M. primiyenious, (=Stylifer primiyenious, Conrad) ; while there are 

 many other more elongated species referred sometimes to this genus, and 

 sometimes to Loxonema, or to Chemnilzia. 



It seems to us it would be better to regard as typical of this genus, only 

 such species as have developed, in a greater or less degree, the fold and thicken- 

 ing of the inner lip, nearly or quite all of which, so far as our observations 

 go, are the shorter forms. The more slender, elongated species, with a com- 

 paratively small body whorl, somewhat extended below, and without any 

 thickening of the inner lip, should, we think, be placed in a separate section, 

 either of this genus, or of Loxonema, or constitute a distinct group from both. 



Macroceeilus medialis. Shell of medium size, rather thick, rhombic, oval ; 

 spire depressed conical, acutely pointed at the apex, forming near one-third 

 of the entire length. Whorls six to six and a half, convex, increasing some- 

 what rapidly in size ; last one large, but not ventricose, the widest part being 

 near the middle ; suture distinct. Aperture rather narrow, oval, acutely 

 angular above, and narrowly rounded below ; outer lip sharp, nearly straight, 

 or but slightly prominent in the middle. Columella a little sinuous about half 

 way up the aperture. Inner lip thickened to the top of the aperture, but not 

 provided with a distinct fold or prominence below, marked by small, regular, 

 obscure transverse striae or wrinkles above the middle. Surface apparently 

 smooth, but showing under a lens traces of fine, very obscure lines of growth. 



[Oct. 



