414 FOSSIL OSTREID^ OF NORTH AMERICA. 



PLATE LXXIV. 



- Fig. 2 (lower). Jh, auricle ; 6m, body-mass; c?, cloaca; j, gills ; i aud i', intestine; 

 /, liver, witli its ducts opening into tbo stomach ; M, adductor; m, month ; ml, man- 

 tle; 0, plane through which tho section represented in Fig. 3 was cut; p, outer cor- 

 rngated surface of inner or Idwer palj) ; i', vent ; ve, ventricle. 



Fig. 3 (upper). Section through the plane o of figure 2, viewed from the anterior 

 side, and enlarged .about two diameters ; a' and a", dorsal and ventral branches of 

 the anterior aorta in section ; hr, branchial vessel ; c, connective tissue; g, gills in 

 section ; g', internal cavities of the gills ; ge, layer of generative tissue or reproductive 

 organ ; i, », cross- sections of the intestinal tube, showing the peculiar form of the in- 

 ternal cavity; J, liver or hepatic ti.ssue ; mt, mantle; sb, suprabranchial or Tvater 

 spaces above the gills; st, cavity of stomach; ve, vena cava. 



