204 ON THE NAIADES, 



Baron de Ferussac, which Lamarck described, and I convinced the 

 Baron that it was only a jjictorum. 



Unio cariosa. The two specimens described are both in the cabi- 

 net of the Duke de Rivoli. The first is a bad specimen of Say's cario- 

 sus. The other (Var. 2). is a bad specimen of the Jilasmodonta mar- 

 ginata (Say). One of the habitats, Lake Erie, is an error ; it is found 

 only in our waters east of the Alleghany mountains. 



Unio sjmria. This species is mentioned by Lamarck as being in the 

 museum of the Garden of Plants. I did not see it there, nor do I 

 know it to be in any other collection. 



Unio australis. The same remarks apply to this species. 



Unio anodontina. I examined the individual described under this 

 name in the collection of the Duke de Rivoli. It proved to be a spe- 

 cimen of U. marginalis, which species is yet known to inhabit only the 

 fresh waters of India. Lamarck says it comes from Virginia, which is 

 certainly an error. 



Unio suborbiculata. This is only a rotundata, as mentioned before 

 in my observations on that species. 



Hyria avicularis. This is the Mya syrmatophora of Gronovius, 

 Gmel., Dill., &c. : avicularis should therefore be abandoned. Lamarck 

 is not certain of the habitat of his specimen, but believes it to be from 

 Brazil. I have seen in Paris a specimen brought by Spix from that 

 country.* 



Hyria corrugata is remarkable for the folds on the umbones, and ii 

 a very distinct species. — They are both in my cabinet. 



Anodonta cygnea. The well known Mytilus cygmus of Linnaeus 

 and others. Of the various forms of this there have been created per- 

 haps a dozen diflferent species. 



Anodonta anatina resembles very closely the cygnea^ but is most 

 probably a distinct species. Poiret asserts that this species is ovipa- 



* This traveller brought also the Castalia ambigita, which, Lamarck says, seems to be iiii- 

 viatile, but which he nevertheless separates from the Naiades, to which it naturally belongs, 

 and not to the family Trigoniana. Both the sheUs are figured in Spix's beautiful work, but 

 described with too little attention to previous writers. 



