1917.] NATURAL SCIENCES OF PHILADELPHIA. 145 



ventrally and posteriorly, it finally reaches the region of the accessory 

 reproductive apparatus, where it breaks up into several distinct 

 branches. One of these disappears from view among the coils of 

 the vas deferens, two or three minute twigs enter the penis, and in 

 two specimens nerves have been traced into the seminal receptacle 

 and into the oviduct adjacent to its external opening. 



Pll arises from the antero-ventral border of the pleural ganglion. 

 In one case it was represented by two nerves, but whether single or 

 paired, it directs its course dorsally, and branching repeatedly is 

 distributed to the dorsal body wall in the neck region. 



P12, a somewhat stronger nerve than Pll, near which it originates, 

 extends in a postero-dorsal direction and after giving off one or two 

 small nerves enters the most anterior and largest lappet. 



P13 arises close to P12, at times fused with it basally, and likewise 

 courses dorsally and posteriorly as far backward as the anal opening. 

 Throughout its extent it gives off branches to the first lappet, which 

 is also innervated by a branch from P12, and also to the second and 

 third lappets. As the third lappet has no counterpart on the right 

 side of the body, the corresponding nerve is distributed to the region 

 about the anus. Attention has been called to the fact that the 

 third lappet and anal region are likewise innervated by branches of 

 P2. 



P14 courses ventrally and after dividing becomes lost in the con- 

 nective tissue and muscle fibers of the body wall close to the anterior 

 margin of the foot. 



Buccal System. — From the postero-ventral face of the cerebral 

 ganglia the cerebro-buccal connectives arise, and coursing around 

 the sides of the pharynx or esophagus unite with the buccal ganglia 

 (PI. XIII, fig. 10, B) at the sides of the digestive tract. The buccal 

 ganglia are more or less globular bodies, and in addition to the 

 cerebro-buccal coimectives each is attached to three other nerves, 

 of which one is the commissure extending beneath the pharynx to 

 join its fellow of the opposite side. Of the remaining two nerves 

 one is comparatively short, and extending anteriorly unites almost 

 immediately with a nerve originating more dorsally from the cerebro- 

 buccal connective. Beyond this point of union the combined bundle 

 extends anteriorly and ventrally, and after forming a plexus becomes 

 lost among the muscles of the pharynx. The last buccal nerve to be 

 considered pursues a posteriorly directed course from the buccal 

 ganglion, and very soon unites with the smaller of the two pedal 

 commissures. Posterior to this point it continues along the sides of 

 10 



