110 TRANS. OF THE ACAD. OF SCIENCE. 



markings, and for several years I have had it in ray cabinet 

 under the latter name. A closer examination, however, 

 shows points of difference which appear to me to be of spe- 

 cific value. The strife of our shell are finer and more crowd- 

 ed ; the dorsum is more broadly rounded, and the umbilicus 

 is proportionally smaller. 



This very handsome species was found by Dr. Geo. G. Shu- 

 mard in a dark compact Limestone supposed to belong to 

 the Coal Measures, on the farm of Mr. J. Blackburn, in the 

 Choctaw Nation. 



Straparollus magnificus, n. sp. 



Shell unusually large, smooth, or marked with fine striae, 

 discoidal ; umbilicus wide, equal to about one half the diam- 

 eter of the shell, and exhibiting from three to four volutions; 

 suture deeply impressed ; volutions very slightly embracing ; 

 width from dorsum to suture less than the height ; dorsum 

 broadly and somewhat deeply excavated, with the dorso- 

 superior and inferior margins obtusely angulated; under and 

 upper surfaces marked with a revolving series of large and 

 somewhat prominent nodes, which are situated nearer the 

 umbilical than the dorsal margin, and of which in the last 

 volution about sixteen can be counted in each series; exte- 

 rior to the nodes the surface is flattened ; umbilical margin 

 rather strongly rounded to the suture. 



Dimensions. — Diameter, 10 inches; height of aperture, 5 

 inches ; width of same, 3| inches. 



The specimen is composed of silex, and a portion of the 

 matrix is so firmly attached to the shell that it is impossible 

 to remove it so as to exhibit the spire. 



This, the largest known species of the genus, is in the cabi- 

 net of Dr. A. Litton of St. Louis, by whom it has been kindly 

 loaned to me for examination and description. It was sent to 

 Dr. Litton from Tennessee by his brother, who obtained it 

 from a person who stated that it was found in Kentucky. 

 Its precise geological position is unknown, but some fossils 

 which adhere to the matrix lead me to believe that it belongs 

 to some one of the divisions of the Carboniferous System. 



Proetus Proutii, n. sp. 



Body subelliptical or subovate, length about one third 

 greater than the width, moderately elevated ; head nearly 

 semicircular, with the genal angles produced posteriorly to a 

 point opposite the sixth thoracic segment; border of moderate 

 width, a little convex, and marked with a very shallow groove, 

 internal to which is a deeper groove separating the border 

 from the cheeks; facial suture very sinuous, and reaching the 



