1888.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 453 



manner that it is absolutely impossible to assign them to any species. 

 The Derby specimens as a rule are smaller, less solid, and duller col- 

 ored than those from Laredo, or from different points in Mexico. 

 Specimens from Lee County, Texas, are very ventricose, rather thin, and 

 covered with a loose, shaggy epidermis. Some of the Indian Territory 

 shells show the tooth on the columella: in others it is wholly want- 

 ing. There are specimens in the lot from Derby having much the color 

 of scJiiedeanus var. mooreanus, but which are longitudinally striped 

 and have dark purplish brown interiors. The variation in the leno-th 

 of specimens in my suite is from 16 to 33 mm , the larger specimens being 

 from Mexico. I believe that the metropolis of this shell is Mexico 

 where it is larger, solider, smoother, and more highly colored than far- 

 ther north; that in its northern limit — the Ozark and Cumberland 

 Mountains — it is usually smaller, thinuer, and less developed in every 

 way than farther south. I will add that Dr. J. A. Singley, of Giddiugs, 

 Tex., a man of much experience as a collector and a careful student, 

 fully agrees with me in the above conclusions. 



Succinea grosvenori Lea. 



Fort Gibson, along a little stream in the town. 



These shells agree perfectly with figure and description in Binney's 

 Manual of American Laud Shells, page 344, but I can not see that they 

 differ essentially from S. luteola (Gould), which I found in great quanti- 

 ties in southern Florida and in western Nebraska. The western Ne- 

 braska shells are a trifle less inflated, and perhaps a little duller iu 

 color than those from Fort Gibson. The Succineas of the United States 

 seem to be in a good deal of confusion and are troubled with a great 

 many names, and when extensive suites from all over the country are 

 carefully studied, I have no doubt that the number of so called species 

 will be greatly reduced. 



Helicina tropica Jan. 



The form of H. orbiculata called by this name was found abundantly 

 at Fort Gibson and near Striugtown. 



Physa heterostropha Say. 

 McAllister; Fort Gibson. 



Planorbis trivolvis Say 

 McAllister; Vinita. 



Sphaerium contractum Prime. 



Pond at McAllister ; Cabin Creek, Vinita. 



Sphcerium stamineum Conrad. 

 Cabin Creek, Vinita. 



Unio camptodon Say. 



Pond at McAllister. 



