CONCHOLOGICAL WRITINGS. 67 
V. FLUVIATILE 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 aS. G. of DMelania, 
[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 belowit, 
giving the opening a subquadrangular appearance. Small streams 
of West Kentucky, one inch long. 
22. Melania 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 8. G. Ambloxus. 
23. Melania 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 Helix by an ombilic 
and a callous tooth above it in the opening. Severalsp. 1. A. 
nodosum, 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 
atooth. 1. M. 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: 
