4 8 



THE AMPH1NEURA 



The two ventral or pedal cords are united beneath the digestive 

 tract by numerous transverse anastomoses. The two lateral or 



V 



Fio. 30. 



Diagrams of the excretory and reproductive organs of Ainplmienra. C, Proneomenia; D, 

 Chiton. Br, ctenidia; Cl, cloacal or pallial chamber of 1'roneomenia ; g, external aperture of 

 the genital duct of Chiton ; N, renal organ ; 0, gonad ; P, pericardium ; r, rectum ; , external 

 aperture of renal organ of Chiton. (From Lankester, after Hubrecht.) 



pallial cords are united posteriorly, 

 dorsad of the anus, by a thick supra- 

 rectal commissure (Fig. 31, VIII). 



The cerebral commissure inner- 

 vates the palps, the lips, and the 

 muscles of the buccal bulb. Below 

 the buccal bulb it is prolonged into 

 an anterior labial commissure, which 

 in turn gives rise to a stomato-gastric 

 commissure : the last-named is to 

 some extent ganglionic and has two 

 branches, which unite with those of 

 the opposite side on the upper and 

 under side of the pharynx, and also 

 . with the infra -oesophageal subrad- 



i, mantle; ii, mouth; ill, foot; iv, ular commissure. The subradular 



gills ; V, anus ; VI, right renal pore ; VII, .. . ,. 



right genital pore (these two pores are Commissure supplies a pair of ganglia 

 better 8 een on the left-hand 8 i5e of the which are j n dose connection with 



a peculiar sense-organ lying on the 



floor of the mouth, in front of the radula. The labial and sub- 

 radular commissures, together with the subradular organ, correspond 

 to the homonomous parts in the Scaphoda and Cephalopoda. 



VI 



Fio. 



Ventral aspect of Acanthoplet 

 i ; III, 



