NERVOUS SYSTEM 



393 



visceral mass with the foot ; the two pedal ganglia are so 

 closely united as to form a single bilobed mass. From each 

 cerebro-pleural ganglion there further proceeds a long cerebro- 

 visceral connective, which passes directly backwards through 

 the kidney and ends in a visceral ganglion (Figs. 93 and 95, 



Fig. g6. — Diagr.im of the circulatory system of Anodonta. 

 The blood received from the auricles (a;/) is pumped by the ventricle (?') into the 

 aorta {ao) and thence passes to the mantle {art^.) and to the body generally 

 {_art^.^. The blood which has circulated through the mantle is returned directly 

 to the auricle : that from the body generally is collected into the vena cava (?'. c), 

 passes by nephridi.al veins {7iph. v) to the kidneys, thence by afferent branchial 

 veins (a/i br. v) to the gills, and is returned by efferent branchial veins {ef. br. r') 

 to the auricles ; pc. pericardium. (From Parker and Haswell's Zoology.) 



C, V. gn) placed on the ventral side of the posterior adductor 

 muscle. The visceral, like the pedal ganglia, are fused 

 together. The cerebro-pleural ganglia supply the labial 

 palps and the anterior part of the mantle ; the pedal, the 

 foot and its muscles ; the visceral, the enteric canal, heart. 



