74 Trans. Acad. Sci. of St. Louis. 



gan Co. (16) ; Niangua River, Hahatonka, Cam- 

 den Co. (15) ; Possum Creek, Camden Co. (21) ; 

 Springfork, Camden Co. (52) ; Prairie Hollow 

 Creek, Coellida, Camden Co. (13) ; Flat Creek, 

 Pettis Co. (14); Shoal Creek, Barry Co. (15); 

 Flat Creek, Barry Co. (6) ; Roaring River, 

 Barry Co. (striped) (8) ; Same (light color) 

 (9); Thatcher Branch, Benton Co. (14); Cur- 

 rent River, Van Buren, Carter Co. (20) ; Mc 



Spring, Howell Co. (12) ; Teague Creek, Web- 

 ster Co. (10) ; James River, Galena, Stone Co. 

 (5) ; North Fork Soc River, Greene Co. (17) ; 

 South Fork Soc River, Greene Co. (20) ; Cen- 

 ter Creek, Sarcoxie, Lawrence Co. (13) ; Spring 

 River, Verona, Lawrence Co. (20) ; Spring 

 River, Carthage, Jasper Co. (20) ; Branch, 

 Carthage, Jasper Co. (8) ; Lost Creek, Seneca, 

 Newton Co. (17); Shoal Creek, Newton Co. 

 (16); Cow Skin River, Macdonald Co. (18); 

 Butler Creek, Noel, Macdonald Co. (9). 



The genus Goniobasis is more widely distributed than 

 the Pleurocera, and more species of it have been de- 

 scribed than of the latter. As early as 1873 nearly five 

 hundred species of Strepomatidae had been described, 

 they being exceedingly abundant in Tennessee and ad- 

 joining territory. At that time Tryon stated that the 

 Mississippi river from its junction with the Ohio to its 

 mouth seemed to have formed an insurmountable bar- 

 rier to the dispersion of these shells. However in the 

 same work he gave the types of one species from Potosi, 

 Missouri, and of another from Saline county, Arkansas. 

 This latter probably, under the name sordida was the 

 one that he stated was found on both sides of the Missis- 

 sippi. I cannot agree, however, that plebeius is a syn- 

 onym of sordida, in which the whorls are convex, while 

 in plebeius they are smooth and flattened, and the angle 

 around the body whorl is generally present. These are 

 also characteristics of cubicoides, a species described 



