48 THE AMPAHINEVRA 
The two ventral or pedal cords are united beneath the digestive 
tract by numerous transverse anastomoses. The two lateral or 
Fic. 30. 
Diagrams of the excretory and reproductive organs of Amphineura. C, Proneomenia; D, 
Chiton. Br, etenidia; Cl, cloacal or pallial chamber of Proneomenia ; g, external aperture of 
the genital duct of Chiton; N, renal organ; O, gonad; P, pericardium ; 7, rectum; wu, external 
aperture of renal organ of Chiton. (From Lankester, after Hubrecht.) 
Fic. 30%, 
Ventral aspect of Acanthoplewra incana. 
I, mantle; II, mouth; III, foot; IV, 
gills; V, anus; VI, right renal pore; VII, 
right genital pore (these two pores are 
better seen on the left-hand side of the 
body). 
pallial cords are united posteriorly, 
dorsad of the anus, by a thick supra- 
rectal commissure (Fig. 31, Vill). 
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-gastrie 
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 
commissure supplies a pair of ganglia 
which are in close 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. 
