GONIOBASIS. 299 



J. Heavy, piipccform or cylindrical species. 

 199. G. cylindracea, Conrad. 



Melania cylindracea, Con., New Fresh-water Shells, p. 55, t. 8, f. 10, 1834. MOller, 

 Synopsis, p. 47, 1836. Bixxey, Check List, No. 84. 



Melania cyUndrica, Con., Wheatlev, Cat. Shells, U. S., p. 25. Reeve, Monog. 

 Melania, sp. 311. Brot, List, )). 32. 



Melania oppugnata. Lea, Philos. Trans., x, p 300, t. 30, f. 9. Obs., v, p. 56. Bin- 

 key, Check List, No. 190. 



Description. — Shell subcylindrical, smooth, with a short spire, the 

 whorls of which are small ; apex eroded ; body-whorl angulated, 

 obtusely rounded above, and at base ; aperture -gis. 576. Fig. 577. 

 more than half the length of the shell, narrow, 

 much contracted above. 



Observations. — This species is remarkable for the 

 rude, almost deformed, whorls of the spire. It 

 inhabits the Tombigbee River on the soft limestone 

 banks, and is generally coated with a calcareous deposit. — Conrad. 



Fig, 576 is a copy of Mr. Conrad's original figure. Fig. 577 

 is from an excellent specimen in Coll. Smithsonian. The 

 numerous shells before me vary in color from brown to dull 

 light green. Whilst most of them are unadorned, a fcAV are 

 banded with dark green. The identity of cylindracea and 

 oppnrjnata is conceded by most American conchologists. The 

 following is the description of the latter with a copy of the 

 figure. 



Melania oppugnata. — Shell smooth, truncate, cylindrical, very thick, 



yellowi.sh horn-color; spire cut ofl"; sutures large and very irregularly 



impressed ; whorls very much compressed, geniculate above ; aper- 



_ ture very long, very much narrowed, above callous ; within 



Fig. 578. J ». .r 



white ; columella twisted, and very much thickened above. 

 Ilabitfit. — Alabama River. 

 Diameter, '41; length, ? 



Observations. — This is a very remarkable species. The 

 two specimens before me are both cut off, leaving little more 

 than the body-whorl. When taken they were evidently living and 

 healthy specimens, but the eroded and fractured spires give them the 

 appearance of old and diseased shells, Avhich is by no means the case. 

 The upper part of the whorl, along the suture, is irregularly frac- 



