JOURNAL OF ENTOMOLOGY AND ZOOLOGY 143 



number 3 also going to the tentacle and the sub-pallial ridge, 

 and 5 and 6 giving branches to a gland in the mouth muscles. 

 Number 4 is a very small nerve which rims forward to the 

 muscles of the body wall. The nerves of the pleural portion 

 are three in number, the first two originating as one nerve 

 which soon branches. They may be called the anterior (7), 

 median (8), and posterior (9), mantle nerves, as they supply 

 the whole length of the mantle. The main trunk of any of these 

 mantle nerves lies in the liody cavity, close to the body wall 

 for most of its length, liut finally passes through the body wall 

 and lies near the large lateral blood sinus. Branches cross the 

 body wall just lielow the large sinus, usually between it and 

 one of its liranches, and run along just outside of it, giving 

 off branches to the papilla\ These branches usually originate 

 near the branches of the sinus and the branches of both systems 

 in the papilla are closely connected. The nerves that go to the 

 jiainllse are large and have some ganglion cells near their 

 origin. They give numerous fibres throughout the length of 

 the papilla, and finally terminate around the gland at the apex. 

 The pedal ganglia are situated below the posterior part of 

 the cereliro-pleural and extend slightly beyond the lateral mar- 

 gins, so that they are usually visible from above. They are 

 nearly spherical and measure about 250 microns in diameter. 

 They are joined to the cerebro-pleural ganglia by two con- 

 nectives, placed close together, the fibres of one passing to the 

 cerebral and of the other to the pleural portion, and to each 

 other by commissures which are closeh' connected with each 

 other and with the visceral commissure for the larger part of 

 their course, but have separate origins. The pedal ganglia give 

 off a pair of very small nerves that run forward to the body 

 wall (14), and anterior (15), median (16), and posterior (17) 

 pedal nerve. These run along inside the muscles of the body 

 wall at the angle of the side and foot, giving otf branches with 

 ganglionic enlargements, which branch and rebranch, sending 

 fibres to the muscles, skin, and glands of the foot. They also 

 give small branches to the muscles of the body wall at the 

 side and foot. The pedal ganglia also give off another pair of 



