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Description.- "A. testa -pellucida rhorn'oidali anterius oro- 

 ducta posterius truncata decussatim striata; natibus reraotis, mar- 

 p-ine posterius hiante ; hiatu ovato ciliato." (Gmelin, 1791) 



The Bov/den s pecimens are of medium size, sub trapezoidal in 

 outline, somev;hat compressed; asymmetri callj rounded anteriorly, 

 posterior end trxincated above, acutely produced below; posterior 

 rid?-e lovr and broad; umbones low, situated at about the anterior 

 fourth of the length; external scalpture of numerous, sharply cat 

 closely spaced radial ribs of different width, being narrowest 

 in the central portion of the shell; the ribs occasionally '^.icho- 

 tomous or the interspaces with s econdary , intercalate"! radials; 

 ribs nodulated at irregular intervals, the ribs beirjf widest and 

 strongest, the intercostal S"o£ces widest and the nodules most 

 prominent on and behind the posterior rid re; cardinal area of med- 

 ium width, crossed by several diverging lig anient g:rooves; teeth in 

 an ^interrupted scries; but the me'ian teeth very short; inner 

 margins with irregular, inconsoicuous crenulations. 



Si'. ens ions .- length, 26.5 mm.; alt., 13 mm.; semidiam. , 5.8 

 mm.; length of hinge, 15 mm. 



Remarkfe .^ ITum.erically this species is well represented, but 

 the majority of the specimens are much smaller than the one meas- 

 ured. Some irre'ularity in shape and nroportions is noticeable. 

 A, Candida may be recognized by its somewhat compressed valves and 



