200 



THE ORGANIZATION 



perpendicular plane, and you will have the head (m) of the 

 animal turned from you, its tail nearest to you, and its back 

 upwards. Consequently, the flat valve is the right one and the 

 hollow valve the left. 



V Wrt 1 



Fig. 121. 



Taking off, now, the right valve, and letting the other one lie 

 over a little in your left hand, but in the same relative position 



Fig. 121. Ostrea Virginica. L. Natural size. The right mantle of the Oyster 

 removed, and the internal organization displayed, sh, the anterior, and sh l the 

 posterior end of the shell ; Jin, the ligament which acts as a hinge to the shells ; 

 mn, the line along which the right mantle was cut away from the left ; wm 1 , the 

 edge of the left mantle ; m, the mouth; st, stomach ; st 1 , posterior end of st ; st 2 , 

 fi>st bend of the intestine (in) ; m 1 , the intestine where it is buried in the 

 liver (I, Z 1 ) ; an, posterior end of the intestine ; I, Z 1 , the upper and lower sides 

 of the liver ; I, the right, and fl the left halves of the outer, leaf-like appendage 

 of the mouth ; t' 2 , the edge of the inner, leaf-like appendage ; gl, the anterior, and 

 gP, the posterior ends of the right and outer gill ; gl 1 , gl*, the inner gill of the 

 right side ; gfi, gl 5 , the inner gill of the left side ; h, the auricle, and A 1 the 

 ventricle of the heart; ao, the posterior, and ao 1 , the anterior aortas, or dis- 

 tributing branches of the circulatory system ; pv, the branchio-cardiac vessels 

 returning the blood from the gills to the heart ; v, v l , blood-vessels in the mantle ; 

 ov, the position of the reproductive organ, just behind the liver ; ms, ms 1 , the two 

 halves of the adductor muscle. Original. 



