220 NERVOUS SYSTEM. 



c, c y ) on each side of the crop (,) the aorta (n, 0,) and the 

 salivary glands (ra,) and above the branchiae, and the genital 

 organs. By removing the anterior supra-cesophageal heart- 

 shaped labial ganglion, and the O3sophagus, the great lateral 

 sub-oesophageal pedal ganglia (/,) are perceived to send for- 

 ward large nervous trunks (d, d, d, e, e,) which extend rami- 

 fying through the central canal of each arm along with the 

 blood-vessels. A separate nervous tract, like that seen in 

 the dorsal columns of the cephalopods, is seen to pass back- 

 wards along the sides of the supra-cesophageal ganglion of 

 the buccinum and other gasteropoda, and having the same 

 pellucid appearance as the simple ungangliated nerves of 

 most invertebrata ; the same tract of simple nerves is seen in 

 the symmetrical columns of conchiferous mollusca especially, 

 as in the cephalopods, at the great posterior pair of symme- 

 trical ganglia. The dorsal columns prolonged from the brain 

 are more approximated, parallel, and lengthened in the loligop- 

 sis and loligo than in most of the naked cephalopods, which 

 corresponds with the lengthened and narrow form of the 

 trunk in these animals. The great nervous trunks, (94. d, d, d,) 

 proceeding from the inferior ganglia (f,fj) anterior to the 

 brain, and accompanying the artery and vein (p,p,pj q,q,g,) 

 through the axis of each arm, send out lateral ramifying 

 branches at regular, short, and decreasing distances from 

 both sides, corresponding with the position of the exterior 

 suckers, and these nervous trunks, diminishing in size as 

 they advance towards the apex of the arm, present through- 

 out their whole course a beaded or knotted appearance, like 

 the nervous axis of a worm. In the long cylindrical trunk 

 of the loligo the nervous columns are continued from the 

 two palleal ganglia, along the whole extent of the dorsal sur- 

 face of the body, and send out numerous lateral branches to 

 the caudal fins, which are seen radiating and ramifying to 

 their extreme margins. As the great trunks of the sympa- 

 thetic in the inverted bodies of the articulated animals occu- 

 py the dorsal region of the abdominal cavity, and the sym- 

 metrical columns the ventral, we find that in the cephalopods 

 where the columns extend along the back; as in the higher 

 classes of vertebrata, the branches of the great sympathetic 

 proceeding from the inferior surface of the brain, extend 

 along the ventral aspect of the abdomen, between the liver 



