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PROCEEDINGS OF THE NATIONAL MUSEUM 



Alabama and Mississippi, as well as Georgia, are thus the areas of 

 primary significance in the eventual resolution of this problem. At 

 least the first two States mentioned should also contain specimens 

 the prostate glands of whicli are intermediate in size, if the two 

 species here considered are actually only geographic races of a single, 

 far-flung species. 



The reproductive systems do not vary appreciably within the range 

 here assigned to the nominal species osceola. 



Summary of variability in several structural characters in the species of the Vitrea 



group 



Distribution. — From extreme southeastern Virginia south into the 

 western panhandle of Florida, inferentially southward into the 

 peninsular part of that State. This is a distributional pattern char- 

 acteristic of a great many species of plants and animals, possibly 

 developing as a consequence of (1) recession of the shore line during 

 the Tertiary, and (2) the simultaneous dissection of the old Cretaceous 

 peneplain of eastern North America with the destruction of lotic 

 habitats in the interior. So far as collection data go, it appears that 

 osceola is largely confined to various species of Procambarus, but its 

 range is less extensive than that even of P. blandingii in eastern 

 United States. Specimens have been examined from the following 

 localities : 



Virginia: charles city county: Roadside ditch about 1 mile south of Provi- 

 dence Forge on Va. Hy. 155, June 2, 1949, P. C. Holt and M. L. Bobb (PCH 226). 

 ISLE OF WIGHT COUNTY: Roadside ditch 2.8 miles east of Franklin on U.S. Hy. 

 68, May 31, 1949, Holt and Bobb (PCH 220). nansemond county: Along 

 U.S. Hy. 58, just west of Suffolk, May 31, 1949, Holt and Bobb (PCH 221). 



