2 7 6 



MANUAL OF ZOOLOGY 



SECT. 



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

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

 gri) 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 a pedal ganglion (pd. gri) situated at the junction of the 



art. 



art 2 



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. /, artery to mantle; art 2, artery to body generally; au, 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- 

 bro-visceral connective which passes directly backwards 

 through the kidney, and ends in a visceral ganglion (v. gri} 



