A Typical Bivalve Mollusk 



rounded ganglia the size of pin heads, ori guard at the sides of 

 the oesophagus. They are joined by a short cord, and send out 

 two pairs of long cords. One pair pass to the pedal ganglion in 

 the fleshy muscle of the food. The other pair go to the visceral 

 ganglion, in the posterior dorsal region. All the organs of the 

 body receive nerves frorn ganglia or connecting commissures. 

 The bivalve ear, when present, is in the foot, at the end of a 

 nerve branch of the pedal ganglion. 



Feeling is the most important sense to the bivalve mollusk. 

 It is not centralised, but the mantle border, and the palpi, espe- 

 cially, are sensitive to touch. Eyes are wanting, except in rare 

 instances. Taste and smell are probably not differentiated from 

 the generalised sense of feeling. 



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