POLYGYRA ALBOLABRIS AND LIMAX MAXIMUS 287 



The median nerve is directed posteriorly to the right (21, 21^), 

 and furnishes nerves to the pulmonary cavity, respiratory orifice 

 and anus. 



The nerve from the right of the ganglion continues posteriorly 

 to the large artery, entering the foot, to a minute oblong gang- 

 lion (4). The ganglion gives off five nerves, of which the larger 

 arises in the outer anterior part, and proceeds along the intestine 

 in close contiguity to the artery. . 



Immediately anterior to this is a small nerve proceeding to the 

 pulmonary cavity. 



From the opposite anterior part proceeds a nerve supplying 

 the hermaphroditic generative organs. 



From the posterior part proceed two nerves supplying the 

 stomach and digestive gland. 



In the inferior part of each of the second pair of infra-esopha- 

 geal ganglia arises a large nerve which passes posteriorly and 

 outward, entering the integument just anterior to the pulmonary 

 chamber; the branches of these nerves supplying that organ and 

 the heart. 



From the posterior part of these ganglia proceed two very 

 large nerves, which continue to the postero-basal part of the 

 animal, parallel to and at a short distance from the pedal gland, 

 giving off several branches to the base of the foot [12, 13^, IS''). 



In the inferior part of the other ganglia arise five other pairs 

 of nerves (15-19), which are inserted in the integument at the 

 sides; and other more numerous nerves, which are inserted in the 

 foot. 



Muscular system 



Plates 19, 20 



The principal muscles, viz, the retractor muscles of the anterior 

 part of the body, the buccal body and the tentacles, have their 

 origin in the inner muscular layer, just posterior to the pulmon- 

 ary cavity on the right side. 



They at first consist of two broad, flat, somewhat connected 

 bands (pi. 19, fig. 1, 2). At about one half the distance to the 

 nerve ganglia these bands are subdivided, giving origin to the 



