THE ALIMENTARY CANAL. 
81 
Fig. 45.— Anatomy of a Gasteropod (Snail): a , mouth; b, foot; c, anus; d, lung; e, 
stomach, covered above by the salivary glands; /, intestine; g , “ liver”; h, heart; 
i, aorta; j, gastric artery; k, artery of the foot; Z, hepatic artery; to, abdominal 
cavity, supplying the place of a venous sinus; n, irregular canal communicating 
with the abdominal cavity, and carrying the blood to the lung; o, vessel carry¬ 
ing blood from the lung to the heart. 
by a narrow “pyloric” orifice, or valve, but is not so clearly 
distinguished from the gullet, so that regurgitation is easy . 42 
g hikealmn f o 
Fig. 46 .—Anatomy of a Lamellibranch ( Mactra): a , shell; b, mantle; c, tentacles, or 
lips; d, mouth ; e, nerves ; f muscles; g, anterior, and n, posterior ganglion ; h, 
“liver”; i, heart; k, stomach; l , intestine passing through the heart; to, kid¬ 
ney; o, anal end of the intestine; p , exhalent, and q , iuhalcnt respiratory tubes, 
or siphons; r, gills; s, foot. 
/ 
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