THE AMPHINEURA 49 
The two great ventral or pedal cords give rise to the pedal 
nerves. 
The two great lateral or pallial cords chiefly send nerves 
to the mantle and the gills, and thus correspond to the whole of the 
Vill 
Fic. 31. 
Nervous system of <Acanthochiton dis- 
erepans, dorsal aspect. I, upper buccal 
commissure; II, upper buccal ganglion ; 
III, stomato-gastric commissure ; IV, labial 
commissure ; V, subradular ganglia and com- 
missure ; VI, anterior (larger) pedal commis- 
sure; VII, pedal cord, with pallio- pedal 
anastomoses ; VIII, supra-rectal pallial com- 
missure; IX, pallial cord; X, pedal anas- 
tomosis; XI, stomato-gastric ganglia and 
radular nerves; XII, oesophageal nerves ; 
XIII, cerebral commissure. 
pleural ganglia and the pallial 
nerves of the other Mollusca ; 
a great part of the viscera 
(genital glands, kidneys, and 
heart) also receives nerves from 
these pallial cords. 
The little differentiated 
head region bears no special 
sense -organ, except that the 
outer edges of the snout taper 
to form the labial palps. The 
lower wall of the buccal cavity 
is furnished with cyathiform 
gustatory bodies, whose nerves 
arise from the cerebral commis- 
Rig. 32. 
Placiphorella stinypsoni, ventral aspect ; 
nearly natural size. a, anus; ci, pallial 
cirrhi; g, gills (between the two rows of 
gills is the oblong foot); m, mouth ; pu, 
mantle ; te, tentacles of the interior edge 
of the mantle. (After Plate.) 
sure ; and, in front of the radula, there is the above-named ‘sub- 
radular organ,” an epithelial projection, with nervous endings, lying 
on the two small subradular ganglia, and probably gustatory in 
function (Fig. 31, V). 
