342 TRANSACTIONS OF THE WAGNER FREE 



species I have found described from the United States is R. unssissippieiisis 

 Meyer, from the Jacksonian. CeritJiidea minnta Gabb, of the Santo Domingo 

 Miocene, turns out, on an inspection of the type, to be a Rissoina. It has not 

 been figured, and there is another Rissoina miniita from Ceylon described by 

 Nevill. Meyer's R. niississippiensis seems to be a good species of the decussata 

 type, small and blunt-tipped, owing to the peculiar planorboid growth of 

 the nuclear whorls. 



Rissoina sp. indet. 



Older Miocene of the Orthaulax bed at Ballast Point, Tampa Bay, Florida, 

 Ball. 



A specimen comprising the last two whorls of a species of Rissoina re- 

 sembling R. IcBvigata Adams is all that is known. It is very much larger than 

 R. Icevigata and quite smooth. It measures 4 mm. long and 2.5 mm. wide. As 

 indicating the presence of the genus in this bed, its occurrence is recorded 

 here. 



Rissoina Johnsoni n. s. 

 Plate 20, figure i. 



Newer Miocene of the Cape Fear River, N. C, C. W. Johnson. 



Shell subconic, polished, not sculptured, with a rounded, plump nucleus 

 of a single whorl and seven subsequent whorls ; sides of the spire flattened, 

 suture distinct, not impressed, sculpture only of extremely fine lines of 

 growth; the last half of the last whorl is somewhat constricted, so that the 

 posterior edge of the suture overhangs a little : periphery of last whorl 

 bluntly angular, base produced ; margin of the aperture continuous, thickened, 

 smooth; the outer lip patulous, within showing an obscure ridge near the 

 posterior commissure. Lon. 5 ; max. diam. 2 mm. 



This pretty species is distinguished by its short, blunt nucleus of a single 

 whorl, its larger size and more conspicuously contracted last whorl, from R. 

 IcBvigata and the other smooth species oi Rissoina so far described. 



Rissoina IsBvigata Adams. 



Jiissoa IcBvigaia C. B. Ads., Contr. Conch., p. 114, 1850. 

 Rissoina lavigata Schwartz, Mon. Rissoina, p. iii, fig. 79, i860. 



Older Miocene of the Chipola beds, Calhoun County, Florida, Burns ; 

 Pliocene of the Caloosahatchie and Shell Creek, Dall and Willcox ; living 

 from Cape Hatteras, N. C, to the Antilles, and also in the Indo-Pacific 

 region, according to Schwartz. 



The specimens have been compared with types named by Prof. Adams, 

 and offer no distinctive characters whatever. The nucleus is peculiar, being 

 of several whorls, shaped like a little Vertigo, which at once differentiates it from 

 the preceding species. 



