Mr. Garner on the Nervous System of Molluscous Animals. 497 



However, in other Cephalopoda, Loligo and Octopus, for instance, the two 

 parts are not so distinct. In the midst of the nerves, which may be justly 

 called the external nerves of respiration, arise the two acoustic nerves (/.) ; 

 thus, as in vertebrated animals, connected at their origin with the nerves 

 distributed to the respiratory tubes. The posterior portion is united to the 

 anterior pedal portion, more or less intimately, in different genera. The aorta 

 passes between them. The nerves supplying the external organs of generation 

 do not arise from the brain, as in Gasteropoda, from their widely different 

 situation. The pharyngeal ganglion (D.), quadrangular in Sepia, bilobed, as 

 in Gasteropoda, in Loligo, is situated in its usual place, at the base of the 

 tongue. Besides muscular and glandular branches (/«.), it evidently sends 

 down filaments (h.) upon the oesophagus. The labial ganglion, which gives 

 two nerves to the pharyngeal, is large and round ; it sends fifteen or twenty 

 filaments (o.) to the lips situated around the maxillae. As described above, it 

 receives a nerve from the upper (sensitive), and another from the lower (motor) 

 portion of the circle. A filament runs across from it, over the upper surface 

 of the superior lobe, towards a round tubercle of nervous matter (/■.), situated 

 upon the optic nerve*. The upper surface of the superior cerebral lobe pre- 

 sents a division into an anterior and a posterior bilobed portion. As described 

 above, it communicates by two chords on each side with the two divisions 

 of the lower portion of the ring, the anterior band being in connexion with 

 the band connecting the labial and pedal ganglia. The anterior division and 

 band are larger in Octopus from the immense size of the feet-j-. The nervous 



purpose of preventing any disarrangement of the parts ; and, lastly, a funnel or siphon, through which 

 the current is evacuated, conveying away the excretions, without their gedning access to and injuring 

 the viscera : with such an apparatus these animals can have no need of vibratile cilia, so common in 

 Moltusca ; and the author has convinced himself that they want them, by examining the excised 

 gills of the adult, and also the living animal of the Sepiola and Sepia just escaped from the ovum. 

 We see the use of so many respiratory nerves from the complication of these organs. 



* This little body has been figured in the Sepia by Mr. Owen {Anat. of the Pearly Nautilus). It 

 equally exists in Loligo and Sepiola. 



t The Octopus creeps, as well as swims, by means of its feet ; and these are the most general loco- 

 motive organs in these animals. Some, however, as Sepiola, swim, by means of the contraction of the 

 sac, in repeated jerks, the head being posterior, using the fins merely as rudders. The Sepia swims 

 entirely by means of these latter organs, and consequently uninterruptedly ; commonly the head is 

 posterior, but when it descends, it does so head foremost. 

 VOL. XVII. 3 T 



