ANODONTA — NERVOUS SYSTEM. 
lOS 
very efficient inter-coiiuiuuiication lietween the different ganglia, as 
tlie least peripheral irritation leads to instant comhined action of 
mantle edge, foot and shell. 
The Cephalic or Cerebral gangiia, or more correctly Cerehro-pleural, 
as the pleural ganglia are intimately fused with the cerebral in this 
grou}), represent the supra-a.‘Sophageal ganglia of Ilel'hv, and are of 
comparatively feeble development in correlation with the atrophy of 
the head and the absence of the accompanying sensory organs. They 
are placed just beneath the skin at the sides of the oral aperture and 
Fi(.. — .Inodonta .slu»\vin.i; the disposition of llie ganglia and the general arrange- 
ment and distrihnlion of the dependent nerves, as seen from the right side after retnoval of the 
right matule loho. and the right cleniilia; the pericartlinm, the ventricle, and the right nephridiinn 
opened up (motlilied after I)u\ernoy, Howes and others). 
a. ad. anterior adductor; <1:.,?. anal siphon ; br. hranchia; br.n. branchial nerve ; b.a. branchial 
>iphoti ; cerehro-pleural ganglia ; c-f*Lp.c. cerel)ro-pleuro-pedal connective ; cerebro- 
pleuro-visccral commissure : d.o. dorsal orifice ; /; foot, with ramifying pedal nerves gastric nerve ; 
t;.n. genital nerve ; /. liver or digestive gland ; ot. otocysl ; /. palps; />.ad posterior adductor ; 
pe<lal ganglia ; />.n. pallial nervous ple.vns, showing numerous small ganglionic enlargements 
anil the general anastomosis of the anterior anil posterior pallial nerves ; 7 . rectum ; ?*.?/. nerve to 
rectum ; visceral or paricto-splanchnic ganglia ; v.n. visceral nerves from pedal centre. 
immediately below and iu front of the pedal-protractor muscle, just 
above the attachment of the mantle lobes, ami comiected together by 
the cerebral commissure j)assiiig above the mouth ; they iiiiiervate 
the palps, the anterior adductor, the region around the mouth and 
the anterior jiart of the mantle. 
The Pedal ganglia are also paired, although the constituents are 
fused together; they are imbedded at the root of the foot, near the 
junction of the muscular with the visceral part, hut rather distant 
i'rom the cerehro-pleural centre, to which they are joined by straight 
connectives, which are easily dissected out. The size of these ganglia 
is always in direct comdation with the development and functional 
importance of the foot. 
