36 AMERICAN JOURNAL 



There seems to be evidence that, in a variable area extending 

 from the south-eastern angle of North Carolina to the western 

 extremity of West Florida, most of the species of Melantlio found 

 therein assume that form known as genicula, Con. Even 31. 

 rufa, always readily distinguished by the peculiar color of the 

 interior and by certain appearances in its epidermis, is found in 

 that region having the form of genicula ! Whether the same 

 local influence reaches westward to the Coosa, modifying the 

 form of the young of '^ ponderosa'' by compressing the whorls 

 below the suture, does not seem clear. Associated species should 

 manifest something of this influence in this instance ; as in the 

 case of gibba, Currier, we find an associate species (quite dis- 

 tinct) assuming a gibbous clavate form. But in the Coosa we have 

 an associated Melantlio (species undetermined or new) that does 

 not in any degree exhibit the compressed whorls that develop the 

 form of genicula. This seems to indicate that the Coosa is not 

 within the area that develops genicula. 



Among Mr. Wheatley's shells were a number of specimens 

 from Corinth, Miss., that were labelled " i!f . coarctoto, Lea." 

 These were thin shells, belonging to a group typified by decisa 

 (as found in eastern Pennsylvania). In form these shells are 

 like some of those slender but heavier shells known as exilis, 

 but destitute of the subangular character so usually impressed 

 on the last whorl of exilis. There are also shells of the same 

 species from Ohio in Mr. Wheatley's collection. The same 

 species from Poland, Ohio, has been distributed by Dr. Kirt- 

 land. It is needless to add that this species is not coarctata ; 

 it is one which, in a careful review of this genus, should have a 

 distinct designation. 



Many other suggestions, less conclusive, have been presented 

 in Mr. Wheatley's collection, but as these suggestions are at 

 present merely speculative it is unnecessary to dwell upon them. 



