1902.] NATURAL SCIENCES OF PHILADELPHIA. 417 



Una rugeli. Of these, the first three are found as far south, at 

 least, as the French Broad, and the last two are offshoots from 

 the summit fauna slightly modified by more favorable conditions of 

 environment. In the same way, of the species inhabiting the coves 

 of the Smoky moimtains, only Polyyyra christyi, P. depilata,^ 

 Pyramidula altcrnata costata, Omphalina fuliginosa polita, Ompha- 

 lina Icevigata latior and perlcevis, Zonitoides patuloides and Punctum 

 hlandianum have not as yet been found to range far enough to the 

 north to mingle with the southern extension of the Roan species. 

 Polygyra chilhoiveensis, P. jyilula, P. monodon cincta and Strobilops 

 labyrinthica strebeli extend at least as far north as the French 

 Broad river, and some of them much further.^ 



Thus we find a large proportion of what were supposed to be the 

 characteristic cove species of these two regions mingled together in 

 the valley of the French Broad. 



On the other hand, just as there are some species peculiar to each 

 of these regions, so we find in the coves tributary to the French 

 Broad drainage a few characteristic forms, which seem to be 

 (without exception) lacking in the coves both to the north and the 

 south. 



From Bluff mountain to Mitchell, throughout this region, there 

 appears a peculiar form of Polygyra andreivsce, which is inter- 

 mediate in size and shape between the typical andrewscd of Roan 

 and Mitchell, and the larger variety normalis, which inhabits the 

 coves from Roan to the Little Tennessee river, and is decidedly 

 characteristic of the French Broad region. It extends, however, 

 north into the lower coves of the Roan region. 



The beautiful and long-lost Pyramidula alternata mordax is 

 apparently restricted to a small portion of this area. 



The almost total absence of typical Gastrodonta gularis, so abun- 

 dant in Roan and in the Smoky mountains, and its replacement by 

 two peculiar forms, var. theloldes A. D. Brown and var. decussata 

 P. and v., is also another striking feature of this region. Again, 

 we find in the French Broad valley a number of species, mostly 

 common and Avidespread, which are found in the Roan region, but 



2 The "P. depilata" collected at Johnson City, Tenn,, by Rhoads (P. 

 A. N. S. P., 1896, p. 493) is P. stenotrema nuda. {Vide these Pi-oceed- 

 zngs, 1900, p. 129.) 



'■^ P. cMlhoweensis, Campbell Co., Tenn. (Wethcrby), and Carysvillc. 

 Campbell Co., Tenn. (Walker and Clapp coll.). 



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