246 



ZOOLOGY. 



The ovaries or testes, as tlie sex of the clam may be, are 

 bilaterally symmetrical, blended with the wall of the visce- 

 ral or liver-mass, and are yellowish. The genital openings 



Fig. 165,— Nervous system of the clam, natural size, a, oesophageal ganglion ; 6, 

 commissure anterior to the mouth ; c, pedal commissure ; d. pedal ganglia ; e, parieto- 

 splanchnic commissures ; /. parietQ-.splanchnic ganglia ; g, branchial nerves ; h, I, pal- 

 lia) nerves ; i, siphonal nerves ; k^ anal nerves \ itt, nerves to the anterior adductor.— 

 Drawn by W. K. Brooks. 



are jDaired and lie near the base of the foot. Both eggs and 

 semen arise from tlie epithelium of the sexual glands. The 

 eggs pass out into the body-cavity, or accumulate between the 



