NATURAL SCIENCES OF PHILADELPHIA. 459 



Length 0*33 inch ; breadth 0-24 inch ; apical angle nearly regular, diverg- 

 ence 60. 



Locality and position. Hodges Creek, Macoupen County, Illinois. Coal 

 measures. 



Pleurotomaria granclostriata. Shell very small, conical subovate, or 

 subtrochiforrn ; spire moderately elevated ; volutions five, increasing rather 

 gradually in size, compressed convex, last one prominently rounded or 

 subangular around the middle ; suture well defined ; aperture subcircular ; 

 spiral band not very distinctly defined, located near the middle of the body 

 whorl and passing around just above the suture on the outer turns ; columella 

 imperforate. Surface ornamented by about twelve or thirteen comparatively 

 distinct revolving lines, eight of which occupy that portion of the body whorl 

 below the band, where they are a little smaller and more closely arranged 

 than above. 



On the upper slope of the whorls above the band, the three or four revolving 

 lines occupying that part of the shell are crossed obliquely by distinct 

 transverse lines, which are so much stronger on the revolving strife than 

 between them, that they present the appearance of small nodes or granules, 

 at the points of crossing. One of the revolving lines, which is larger than the 

 others, passes around on the middle of the revolving band, and is neatly and 

 regularly crenulated by the crossing of the transverse lines. 



Length 0.17 inch ; breadth 0"15 inch ; apical angle regular, divergence 60. 



Locality and position. Hodges Creek, Macoupen County, Illinois. Coal 

 measures. 



Pleurotomaria tenuicincta. Shell small, conical ovate, spire moderately 

 elevated ; volutions seven, obliquely flattened or a little concave above, convex 

 and more or less distinctly angular around the middle, last one tumid below ; 

 suture distinct ; spiral band very narrow, concave, located a little above the 

 middle of the body whorl, and passing around rather below the middle of the 

 others ; aperture subcircular ; umbilical region indented, but apparently not 

 distinctly perforate. Surface ornamented by about eighteen to twenty rather 

 distinct revolving lines, only two or three of which occupy the flattened or 

 concave upper slope above the band, where they are less prominent than the 

 others ; while the two forming the margins of the band are more salient than 

 any of those below ; fine, regularly arranged stria?, which are much more 

 distinct on the slope above, than below the band, mark the whorls transversely. 



Length 0*24 ; breadth - 20 inch ; apical angle a little convex, divergence G0. 



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



Pleurotomaria Pratteni. Shell very small, conical ovate, the length being 

 greater than the breadth ; spire rather elevated, but not acute at the apex ; 

 volutions six to six and a-half, slightly convex, increasing gradually in size, 

 those of the spire more or less distinctly angular around the middle, last one 

 sometimes slightly flattened near the middle just below the angle, and convex 

 on the under side ; suture well defined. Spiral band of moderate breadth, 

 not very distinctly defined, sometimes slightly concave, occupying the more 

 or less compressed middle portion of the last whorl, and passing around so as 

 to bring its lower margin a little above the suture on the other turns. 

 Aperture subcircular; columella arcuate, a little flattened below, and imper- 

 forate ; outer lip thin ; sinus narrow and deep. Surface marked by about 

 eighteen to twenty very small, obscure revolving striae, some twelve or thirteen 

 of which occupy the body whorl below the band, where they are a little larger 

 than those above the angle, and more regularly arranged ; lines of growth 

 very fine and obscure. 



Named in honor of Mr. Henry Pratten, deceased, formerly of the Geological 

 Survey of Illinois. 



I860.] 



