The anatomy of Liicapina crenulata, 469 



the inferior lip. However, if a specimen is properly macerated in 

 nitric acid the connection can be made out with little dissecting. 



The buccal ganglia lie close upon the radular support, between 

 the radula and the pharynx. They can best be seen by removing this 

 part of the alimentary canal. A labio-buccal connective is attached to 

 the posterior extremity of each labial ganglion beside the inferior 

 labial nerves. It runs up through the protractor muscles on the side 

 of the radular supports to the anterior end of the buccal ganglion of 

 that side. One or more nerves {Pm. n) are given olf from the buccal 

 ganglion near the point where the labio-buccal connective joins it. 

 These nerves supply the protractor muscles, running down and out 

 around the sides of the radular supports. From the inner anterior 

 part of the buccal ganglion a nerve of considerable size {Sg. n) passes 

 up and back, through the sugar gland. In this gland branches are 

 given otf, but the main part of the nerve runs back in the lateral 

 wall of the pharynx {Oe.n) supplying both the muscular coats of this 

 part of the alimentary canal and the great digestive glands within. 

 These same nerves continue back into the walls of the oesophagus as 

 far as the stomach. The two buccal ganglia are connected at their 

 posterior ends by the buccal commissure {Buc. c) and at the junction 

 of the two on each side a nerve arises, which extends backward and 

 divides almost immediately, one part going down and supplying the 

 retractor muscles, the other running back along the wall of the radular 

 tube. A small nerve runs forward from the posterior end of each 

 buccal ganglion, supplying the anterior part of the radular tube. 



The Pleural and Pedal Ganglia. The nerves lying in the 

 foot are in the form of thickened cords and without question consist 

 of two elements such as many years ago were noted in Haliotis by 

 Lacaze-Duthiers (59). These, as will be shown later, possess certain 

 characteristics which lead to the belief that they represent the fused 

 pleural and pedal cords. 



Between the pedal chords (Fig. 15 Ped.Ch) are ten or eleven 

 commissures {Fed. com), and from the under side of each of these is 

 a small nerve {U.p.n) going down into the foot. Haller has de- 

 signated this latter nerve as the unpaired pedal, in distinction to the 

 paired pedal nerves (P.P.n) to be spoken of next. These names are 

 certainly appropriate, and their meaning is clear as there are only 

 these two kinds of pedal nerves. From the outer edge of each pedal 

 chord numerous nerves (P.P.n) are given ofif, which go sooner or 

 later into the tissue of the foot. The pleural chords (P. Ch) are 



