btikne:. neetous system of amptjllaeia. 319, 



commissure connecting the pedal ganglia above the pedal artery ; 

 (2) a smaller cylindrical commissure connecting the pedal ganglia 

 beneath the pedal artery; and (3) a flat commissure connecting the 

 pleural ganglia. Of these commissures, the first pedal and the pleural 

 lie in the same plane, closely contiguous to one another, and although 

 quite separate at either end, where they respectively emerge from the 

 pleural and pedal parts of the ganglion mass, are united to one 

 another in the middle of their course, and at this point show their 

 individuality only by a superficial furrow. The second pedal com- 

 missure rises from the ventral surface of the pedal ganglia, and takes 

 a semicircular course from one to the other beneath the pedal artery. 

 Prom its position this commissure should be the most anterior of the 

 ladder commissures that unite the pedal cords. In other respects the 

 nervous system of AmpuUaria, sp., corresponds very closely to that of 

 the three species examined by Bouvier. 



