AXODONTA. 501 



Species of Monocondylcea. 



Corrientesensis, D'Orb. Minuana, D'Orb. 



fossiculifera, D'Orb. Paraguayan, D'Orb. 



Franciscana, Moric. Parchappii, D'Orb. 



glauca, Gould. Vondenbuschiana, Lea. 

 Guarayana, D'Orb. 



Genus BARBALA, Humphrey. 



Animal unknown. 



Shell with the valves generally winged and connate. 

 Hinge with a single linear tooth under the dorsal margin, 

 extending the whole length. 



Syn. Barhata, Sow. Oristaria, Schum. Appius, Leach. 

 Dianisotis, Rafin. Dipsas, Leach, not Laur. Symphy- 

 nota, Swains., not Lea. Dipsax, Voigt. 



Ex. B. plicata, Humphrey , pi. 117, fig. 4, 4, a. 



The species of this genus are all Asiatic in their geogra- 

 phical distribution. 



Species of Barbala. 



discoidea, Lea. plicata, Humph. 



Largillierti, Phil. 



Genus anodonta, Bruguiere. 



Gills free ; eggs received throughout the gill ; anal open- 

 ing not fringed. 



Shell equivalve, ovate, usually rather thin, auriculate, 

 inequilateral, closed ; beaks small. Hinge without teeth, 



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