60 WALTER K. FISHER, 



by slender commissures with the labial ganglia and have no connection 

 whatever with the pedal. 



20) There are two long thick pedal cords, continuations of the 

 pedal ganglia. These are united by |three direct commissures, and 

 supply the foot and spindle muscles. 



21) The innervation of the mantle is complex and wholly typical 

 of the Acmaeidae. From each pleural ganglion, there are two principal 

 pallial nerves, which reach a circumpallial nerve completely encircling 

 the animal near the mantle edge. This nerve is ganglionic to a slight 

 degree, and supplies the finer nerves to the mantle. 



22) On the left side there is a pleuro-osphradial connective, 

 joining the left pleural ganglion directly with the osphradial nerve. 



23) The osphradial nerves arise from the intestinal (or parietal) 

 ganglia of the visceral loop. In the course of each of these nerves 

 there is a ganglion which sends nerves to the osphradium of that side. 



24) A continuation of the left osphradial nerve becomes the 

 ctenidial nerve, at the beginning of which there is a small ganglion. 



25) Each osphradial nerve by two terminal branches, the parietal 

 nerves, is joined to the pallial nerves, posteriorly in the spindle muscle 

 and anteriorly in the mantle. 



26) The nephridial nerves are branches of the posterior parietals, 

 one on each side, and follow the kidney blood collector to the hind end 

 of the animal. 



27) In the mantle hood on the right side there is a curious nerve 

 in the form of a small ring, and another in the median line. These 

 are connected with the anterior parietal of the right side. Their 

 significance is not known. 



28) The nerve supply of the viscera is derived from the stomato- 

 gastric ganglia, the visceral ganglion, and the pleural ganglia. The 

 stomatogastric may be considered the most important center for the 

 alimentary canal. 



Palo Alto, California, May 1, 1903. 



