THE AMPHINEURA 



The two ventral or pedal cords are united beneath the digestive 

 tract by numerous transverse anastomoses. The two lateral or 



it. 



FIG. 30. 



Diagrams of the excretory and reproductive organs of Amphineura. C, Proneoinenia; D, 

 Chiton. Br, ctenidia ; Cl, cloacal or pallial chamber of Proneomenia ; g, external aperture of 

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

 ular commissure. The subradular 



VI 



FIG. 



Ventral aspect of Acanthopleum incana. 

 I, mantle; II, mouth; III, foot; IV, 



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



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

 better seen on the I ie 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. 



