430 Miscellaneous, 



swims more readily than it walks. Moving always in the same direc- 

 tion, it is constantly striking against the same point of the vessel in 

 which it is kept. In general it scarcely survives the operation twenty- 

 four hours. 



When one of the lobes of the supra-cesophageal ganglion of a 

 Byticus has been removed, the power of walking is diminished^ but 

 the animal still swims with great celerity. In either case the insect 

 always moves towards the uninjured side, so that it describes inter- 

 minable circles in the same direction. Thus, when deprived of one 

 of its lobes, the Byticus loses the power of directing itself towards 

 the side of this lobe, from which we may conclude that each lobe 

 presides in the direction of its side. 



2. Total or partial removal of the sub-oesophageal ganglion. — 

 "When this ganglion is entirely removed, the JJytici are totally in- 

 capable of swimming or walking. This is not owing to the paralysis 

 of any of the legs, for each member moves spontaneously and draws 

 back when pinched. The ambulatory feet are even seen to move, as 

 if to walk, and the natatory feet as if to swim. But the insect only 

 moves accidentally ; it neither walks nor swims. 



The exciting power of its motions, and that by which they are 

 coordinated, cease with the removal of the sub-oesophageal ganglion. 

 The insect raises itself on its feet, it advances an ambulatory foot 

 with a natatory one, or even the natatory feet of one side, and this 

 disagreement produces no result. 



These observations lead to the following results : — 



The supra- and sub-oesophageal ganglia and the peduncles which 

 unite them, represent the brain of the Byticus, and exert an incon- 

 testable influence upon locomotion. 



The upper part of the brain, placed above the oesophagus, is the 

 seat of volition and of the direction of the movements. 



The lower part is the seat of the exciting cause and of the^coordi- 

 nating power. — Comptes Rendus, 6 April 1857, p. 721. 



On Spiochsetopterus, a new genus of Annelides from the Coast of 

 Norway. By M. Sars. 



SpiocHiETOPTERus, Sars. 



Corpus filiforme, antice truncatum ibique infra et ad latera labium 

 formans carnosum spathulatum sen infundibuhforme, in cujus fundo 

 OS. Lobus capitalis supra os, parvus, rotundatus, ocuhs nullis. Cirri 

 tentaculares duo longissimi et sulco longitudinali ornati. Segmenta 

 novem antica corporis depressa, brevia, mamillis pedalibus conicis 

 sen pyramidalibus solummodo dorsalibus (ventralibus carentibus), 

 setis instructis capillaribus apice subhastato-acuto non in fasciculum 

 congestis, sed seriem transversam sen ad longitudinem mamillarum 

 formantibus, segmentum quartum etiam seta vahdissima apice oblique 

 truncato et denticulo ornato. 



Segmentum decimum et undecimum subteretia, longissima, pinnis 

 seu mamilhs pedalibus foliaceis ornata, scilicet una dorsali fasciculum 



