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PANDORID^. 



THE PANDORA TRIBE. 



The genus Pandora^ and its foreign ally, Myodora, pre- 

 sent peculiarities which prevent our including them, as 

 many have done, in the tribe of which Corhula is the type. 

 Their extremely unequal and irregular shells, and peculiar 

 modifications of hinge and, above all, the minute structure 

 of the shell, which resembles that of the margaritaceous bi- 

 valves, aiford sufficient and easily-recognizable characters, 

 derived from the hard parts ; whilst the singular conforma- 

 tion of the branchiae, partially reduced by suppression, the 

 small foot, and the united tubes with diverging orifices, 

 present a combination of features in the animal strikingly 

 distinguishing it from that of the neighbouring tribes with 

 closed mantles. The small extent of the family, as at pre- 

 sent known, is no objection to its claim to rank as such : 

 value of character, and not number of species, must ever 

 be the only sound ground for the limitation of either tribe 

 or genus. 



PANDORA, Lamarck. 



Shell inequivalve, inequilateral, nacreous ; one valve 

 flat, the other more or less convex. Hinge composed of a 

 primary tooth in each valve, with corresponding pits. 

 Ligament internal. Muscular impressions weak, rounded ; 

 pal leal with a very slight sinus. 



