COMPARATIVE ANATOMY 



Fig. 18 



A. Nervous system of Helix aspersa, an example of the euthyneurous condition in 

 which the pleural, visceral, abdominal and pedal ganglia are fused to form a 

 suboesophageal ganglion mass. B. Nervous system of Limnafa, an example of 

 the short-looped euthyneurous condition in which the ganglia are separate 

 (after de Lacaze Duthiers). C. -Nervous system of Paludina. 'viiripara, an 

 example of the streptoneurous condition. aM, abdominal ganglion ; /rucc, 

 buccal ganglia ; cer, cerebral ganglia , cpc, cerebro-pedal connective ; cvc, 

 cerebro-pleural connective ; gd, conjoined genital duct ; nf, facial nerve ; 

 n gi genital nerve; nle, -exterior labial nerve; //, internal labial nerve; 

 nop, optic nerve ; />, pedal nerves ; npl, left pallial nerve ; npm, median 

 pallial nerve ; n/>n, penial nerve ; npr, right pallial nerve ; o, osphradium ; 

 oe, oesophagus ; otc, otocyst ; ped, pedal ganglion ; ph, pharynx ; //, pleural 

 ganglion ; rs, radula-sac ; sl>g, suboesophageal ganglion mass ; s, sub-intestinal 

 ganglion ; sj>, supra-intestinal ganglion ; vis, visceral ganglion ; vn, visceral 

 nerve. 



