3IARCAKIT A N A . 



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*Hildrethiana. 1 Lea. 

 I 'ki'o Hildrt thianus. 

 Al. ambiguaf Say. 



Lea. 



*ilehiscens. 2 Say. Lea. 



Unio d< hiscens. Say. Desk. Hart. 

 Unio oriens. Lea. 



OBOVATE. 



*Coimasaugaensis. Lea. 

 *Spillmanii. Lea. 



AECL'ATE. 



^margaritifera. 3 Lin. Lea. Cooper.* 

 Mija margaritifera. Lin. Mill. 



Born. Schrot. Pennant. Don. 



Chem. Knorr. Da Costa. Dill. 



Desh. Wood. Mat. Monta. 



Mtihl. Nil. Schreib. Cuv. 



Rossm. Dup. Eat. Chenu. Moq. 



crassissima. Klein. 



Margaritana fluviatilis. 5 Schum. 

 Margaritana arcuata. Stimp>son. 

 Margaritana ( Unio) Mongolicus. 



Mid/. 



f ARCUATE. 



Unio ehngata. Lam. Mich. Bouil. 



Nils. Puton. Potier. Dup. 



Merm. Gras. 

 Unio sinuata. Stud. Pfeif. 

 Unio Roissyi. Mich. Desh. Gras. 

 Unio margaritiferus. Retz. Speng. 



Pfeif. Cuv. Drop. Rose. Turt. 



Gaertner. 6 Menke. Waard. Rossm. 



Dup. Bouil. Alder. Gras. Han. 

 Unio margaritifer. Graells. SchrenJc. 



Midd. 

 Unio rivalis. Zieg. 

 Unio Carolinianus. 7 Bosc. 

 Unio Dahuricus. Midd. Gerst. 

 Alas, margaritiferum. Flem. Broun. 



Macgil. 

 Alas, margaritiferus. Thompson. 



Forles. 

 Alas, elongahi-s. Thompson. 

 Alas, arcuata. Bar. Gould. Adams. 



Migh. Linsl. Dehay. 

 My a arcuata. Rat. 

 Alas.falcata. Gould. 

 Alas. Yuhaensis. Trash. 



1 In the previous editions, this was placed among the Uniones with much hesitation. I now think it 

 groups better with the Margaritanae. Its cardinal tooth is very much like M. Bonellii, and the callus of 

 the dorsal margin is sometimes, in both, so much thickened as to present an imperfect appearance of a 

 lateral tooth. Mr. Say's description of ambigua answers well to Hildrethiana, but I am not sure it is 

 the same, as he has given no figure of it. He seems to have abandoned it, as he does not insert it in his 

 Synonymy. Mr. Conrad also avoids the insertion of it in his Sjnioptical Table. 



2 Mr. Say, in his Synonymy, gives Mr. Rafinesque's name of lata precedence. Mr. Eaton says that 

 An. lata, Raf., is Symphynota tenuissima, Lea. 



3 Klein describes this species under the name of crassissima, but with no generic term. This name 

 has been, by Ferussac and other zoologists, erroneously applied to the large Unio, common to the south 

 of Europe, which Retzius described as Unio crassus, and 1 have given it to Retzius. Klein's crassissiTna 

 is the true Margaritana margaritifera {Mya margaritifera, Lin.), and his figure of it, PI. x. Fig. 47, is a 

 copy of Lister's, Tab. 149, Fig. 4. 



4 Judge Cooper states, under the authority of Dr. Cooper, that the Indians east of Cascade Moun- 

 tains eat this species. 



5 1 adopt Schumacher's generic name because he has priority; but I discard his specific name of 

 fluviatilis because he changed, without anj- reason, the long and well-established specific name of mar- 

 garitifera. 



6 Fide Menke. 



7 I have been, and am still, perplexed about this species of Rose. M. Ferussac considers it the same 

 with Unio obesus (nobis), and I so stated it in my second edition. Recently, I have had access to Rose's 

 description and figure (His/. Nat des Goquilles), which agree better with Margaritana margaritifera 

 than an j' other species; and he refers to the figure of it in Ency. Meth. 



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