246 GILMAN A. DREW. 



PLATE XVI I. 



FIG. i. Animal as seen from the left side with the left shell valve and mantle 

 lobe removed and with a portion of the pericardial wall cut away. A few of the 

 blood vessels are shown. Two thirds natural size. 



FIG. 2. Animal as seen from the left side with the left shell valve and mantle 

 lobe removed, with the alimentary canal shown. Two thirds natural size. 



, auricle ; ba, branchial artery ; bv, branchial vein ; c, cartilage ; e, excretory 

 organ ; /, foot ; fe, free edge of the unattached lamella of the gill ; g, gill ; i, intes- 

 tine ; Ip, labial palp ; m, mantle ; /<?, posterior adductor muscle ; s, stomach ; v, 

 ventricle ; nil, visceral mass. 



