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MANUAL OF ZOOLOGY 



from anything we have yet met with. On each side of the 

 gullet is a small cerebro-pleural ganglion (Fig. 162, c. pi. 

 gn) united with its fellow of the opposite side by a nerve- 

 cord — the cerebral commissure passing about the gullet. 

 Each cerebro-pleural ganglion also gives off a cord, the cere- 

 bro-pedal connective, which passes downwards and backwards 

 to & pedal ganglion (pd. gn) situated at the junction of the 



Fig. 164. — Diagram of the circulatory system of Anodonta. Vessels containing 

 aerated blood red, non-aerated blue. af.br. v, afferent branchial veins; ao, 

 aorta: art. I, artery to mantle; art 5, artery to body generally; an, auricle; 

 ef. br. v, efferent branchial veins; nph. v. nephridial veins; pc, pericardium; v, 

 ventricle; v. c, vena cava. The arrows show the direction of the current. 



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 cere- 

 hro-visceral connective which passes directly backwards 

 through the kidney, and ends in a visceral ganglion (v. gn) 



