1895. PROCEEDINGS OF THE NATIONAL MUSEUM. 309 



From the region of the beaks iu the interior, tiiere springs a series 

 of slight, radiating, irregiihir ridges, and between the outer ends of 

 these are three curious dorsal cicatrices. These are like the posterior 

 cicatrices of an ordinary r)iio, being rounded or semicircular, and not 

 impressed. The posterior muscle scars are very indistinct. 



The beaks are sculptured with somewhat scattered nodules, which 

 are seen very plainly in B. tanganyicensis^ Smith, but not so clearly in 

 B. elonc/ata, Bourguignat. Two specimens of the latter in the National 

 Museum collection (No. 127190), seem to show the remains of a glo- 

 chidium quite distinctly: and this character, the beak sculpture, and 

 the rudimentary cardinal and lateral teeth, induce me to place the 

 group in the Unionida? instead of the Mutelidte, to which it has been 

 assigned. The shells frequently have the posterior end turned to the 

 left or right like those of Tellina. 



Genus ANODONTA, (Bruguiere em.) Lamarck.^ 



In 1792 Bruguiere^ applied the name Anodontites to certain edentu- 

 lous mollusks, properly describing the genus, mentioning Mytilus cyg- 

 ncHS and 31. anaUnus of Linniens, as belonging to it, and describing a 

 new species, A. crispata of Guiana, which is now believed to have no 

 generic relation to either of the other species. In 1797 he figured, with- 

 out text, a large number of species.^ This generic name was adopted 

 by Cuvier, Poiret, Deshayes and others. 



In 1799 Lamarck changed the name to Anodonta,* describing the 

 genus, and citing A. cygnea, Linnteus, as the type. In 1805 Eoissy^ 

 explained that the genus was due to Bruguiere, but that Lamarck 

 changed the termination, because in the nomenclature as then regu- 

 lated, the termination ites indicated that the genus included only extinct 

 species. Dr. Ball has worked out the above jiuzzling synonymy with 

 a great deal of care, and believes that under the rules of nomenclature 

 a., they then existed Lamarck Avas justified in making the change in 

 termination — that Anodonta is synonymous with Anodontites, and that 

 the former should be retained. 



The Anodontites crispata of Bruguiere, from northern South America, 

 is fairly typical of a large grouj) of the genus Glaharis of Gray, which 

 is now placed by v. Iheriug and others in the family Mutelida?. 



The genus Anodonta, as now restricted, consists of Naiades with gen- 

 erally thin, inflated shells, for the most paDrt without sharp angles, and 

 free from sculpture except on the region of the beaks. The hinge line 

 is a regular curve and is not indented iu front of the beaks as is that 

 of JJnio, and this seems to be about the best distinguishing character 



1 Prodrome Class. Coci., p. 87, 1799. 

 2Journ. Hist. Nat., I, p. 131, 1792. 

 sEncycl. Meth., pis. 201-205, 1797. 

 ■• Prodrome 'Class. Coq., p. 87, 1799. 

 6 Hist. Nat. Moll., VI, p. 312, 1805. 



