CONCHOLOGICAL WRITINGS. 6T 



V. FLUYIATILE UNIVALVE SHELLS. 



19. Pleurocera Gonula, Raf. 1818. Seven spires, the first with 

 two or three small angles, the others with only one. River Ken- 

 tucky. My G. Pleurocera, 1819, is perhaps a S. Gr. of Melania, 



[3] 

 but the animal is different, with lateral feelers ; the shell is always 

 conical oblong with the opening oblong oblique acute at both ends, 

 columella flexuose twisted. 



20. Pleurocera Acuta, Raf. 1818. Shell elongate very acute, 

 smooth, nine spires, the first angular in front. Lake Erie. 



21. Pleurocera Quadrosa, Raf. 1816. Conical, smooth, six 

 spires, the first with an obtuse circular angle, and a furrow below it, 

 giving the opening a subquadrangular appearance. Small streams 

 of West Kentucky, one inch long. 



22. Ilelania Rugosa, Raf, Pyramidal acute, nine spires rugose 

 vertically, streams of Cumberland Mountains. I leave the name of 

 Melania to the shells with opening obtuse at the end, or they may 

 form the S. G. Amhloxus. 



23. Ilelania Viridis, Raf. Suboval smooth, five spires, end 

 obtuse, opening oblong. Fine shell, one inch, green, from Licking 

 River. 



VI. LAND UNIVALVE SHELLS. 



24. APLODON, Raf. 1819. Differ from Eelix by an ombilic 

 and a callous tooth above it in the opening. Several sp. 1. A. 

 nodosumi, Raf 1818. Subdepressed, rugose below concentrically, 

 3 nodose spires. In Kentucky. 



25. STENOSTOMA, Raf 1819. Differ from Helix, opening 

 linear with lips, upper lip notched, lower carinated. 1. St. convexa, 

 Raf. Nearly round, both sides convex, smooth, 5 spires. Kentucky. 



26. TOXOSTOMA, Raf. 1819. Differ from the last, by no lower 

 lip nor keel to the opening, which is curved. 1. T. globularis. 

 Globular smooth, 5 spires. In Kentucky. 



27. MESODON, Raf. 1819. Differ from Helix by lower lip with 

 a tooth. 1. 31. maculatum. Depressed, hardly striated, upper lip 

 reflexed, tooth careniform, 5 spires. Fulvous with brown spots. 

 The G. Trophodon differ from this by upper lip notched. The G. 

 Odomphium by having an ombilic. 



28. OMPHALINA, Raf 1819. Differ from Helix by no lips; 



