39 



CHAPTEE YII. 



THEUNEQUAL-VALVED CORBULA. THE TAPERING SPH.ENIA. THE GRACE- 

 FUL NE^RA. THE UNPRETENDING POROMYA. THE PEARLY PANDORA- 



— THE IRIDESCENT LYONSIA. — THE RUDE THRACIA, AND THE SPOON- 

 HINGED COCHLODESMA. 



CORBULID^, PANDORIDJE, ANATINID^. 



The genera of small bivalved mollusca composing these two 

 families are perhaps scarcely different enough to be sepa- 

 rated; they are all distinguished from the preceding fa- 

 milies by the shortness of their siphons. The genera com- 

 posing the three families may be thus enumerated : — 



CORBULID^. 



I. CoRBULA. — The animal is »hort and small, with short 

 united siphonal tubes, both fringed at the openings. 

 The mantle, which is at once the outer coating of 

 the body and the lining of the shell, is closed except- 



