14 THE NAUTILUS. 



the gill-lilaraents while liura they cress them obliquely. Moreover, 

 the septa of the Unionidce are much more closely set (chiefly in the 

 females), and much more regular. 



Margaritana monodonta differs by this structure markedly from 

 all species of Margaiitaiia I know. I have seen the typical Mar- 

 garitana-strinituve not only in Margaritana mar garitif era (L.) (both 

 from Europe and northeastern America), but also in two specimens 

 of Margaritana sinuata (Lam.) (== crassa Simpson, 1, c. p. 678) 

 from near Perpignan, France (sent to me by Mr. W. Israel), and 

 in a number of specimens of Margaritana hemheli (Conr.) from 

 southern Alabama (I am obliged to Mr. H. H. Smith for these). 

 While I thus consider these three species as congeneric (the creation 

 of Pseudunio for sinuata by Haas notAvithstanding), M. monodonta 

 differs from them in an important structure, which undoubtedly 

 represents a higher specialization, a forward step in evolution, and it 

 is, as I believe, entitled on this account to the rank of a separate 

 genus, which 1 propose to call Cumberlandia (Type: monodonta 

 Say). 



As to the distribution of Cumberlandia monodonta, Walker's papers 

 should be consulted (Pr. Mai. Soc. 9. 1910 pp. 137-139, and 

 Nautilus, 25. 1911 p. 57-58). According to this, the metro- 

 polis of it seems to be in the Cumberland and Tennessee 

 Rivers, but it has spread into the lower Ohio drainage, and into 

 Indiana and Illinois. In the Ohio, it was not known, up to the 

 present, above Cincinnati : but I may mention here, that I found 

 last summer (July 13, 1911) a dead specimen of Cumberlandia 

 monodonta in the Ohio River at Biiffingfon Island, near Portland, 

 Meigs Co., Ohio. I also may add, that according to the experience 

 gained by my last year's collecting, it is entirely excluded that this 

 species occurs anywhere in the Big Sandy or Great Kanawha Rivers, 

 and that I do not think that it reached its present range by coming 

 "down" the Ohio. But this will be discussed elsewhere. 



ADDITION TO THE LIST OF M0LLX7SCA FROM MONTE BANO, ALABAMA. 



BY. H, E. WHEELER. 



Through the kindness of Prof. Herbert H. Smith, conchologically 

 the "discoverer " of Monte Sano, and Mr. George H. Clapp, who 



