148 



COMPARATIVE ANATOMY 



(1) Two cerebro-brachial ; (2) two cerebro-infiindibular ; (3) two 

 cerebropleural ; (4) two brachio-infundibular ; (5) two pleuro-infundi- 

 bular ; (6) two pleurobrachial connectives. The close proximity of 

 the visceral ganglia to the peri-ojsophageal mass makes it impossible 

 any longer to distinguish the visceral connectives. 



The cerebral ganglia give rise to tlie'two o])tic nerves (which soon swell into tlie 



enormous optic ganglia at 

 A 



5 



the liases of the eyes), the 

 auditory nerves, the olfac- 

 tory nerves (which for a 

 certain distance fuse with 

 the optic nerves), and the 

 connectives of the buccal 

 ganglia. 



The brachial ganglia 

 send off separate nerves to 

 the arms, which nerves are 

 connected by a hoop-like 

 commissure I'ound the base 

 of the circle of arms. Run- 

 ning through the arms, the 

 nerves swell into succes- 

 sive ganglia which corre- 

 spond with the transverse 

 rows of acetabida. 



The separation of the 

 pedal ganglion into a bra- 

 chial and an infundibular 

 ganglion can be proved on- 

 togenetically and anatomi- 

 cally. There is no such 

 separation in the male 

 Nautilus, the brachial and 

 infundibular nerves spring- 

 ing from one and the same 

 ganglion. In Argonaiita 

 (Fig. 128, F) the separation 



is not externally visible, 

 Fio. 128.— Central nervous system of various Dibranchia, , , . ^ , ,-^. 



from the right side. Allthe figures after Pelseneer. A, Ommato- ^"^ \'^ ^'^^"^"^ (E) we see 

 strephes ; B, Sepiola ; C, Loligo ; D, Sepia ; E, Octopus ; F, Argo- the first traces of it ; in 

 nauta. 1, Cerebral; 2, pedal; 3, visceral; 4, brachial; 5, upper Sepia (D), Loligo (C), and 

 buccal ganglion ; 6, infundibular nerve ; 7, visceral nerve ; 8, optic Sepiola (B) it becomes 

 nerve cut through ; 9 pallial nerve ; 10 brachial nerves ; and in ^^^^^.^ ^^^ ^^^J^.^ evident, till 

 Fig. B the pharynx (m), and CBSophagus (a) are drawn in black. ^ n . ^ , 



finally in Ommatostrcphes 



(A) the distinct brachial ganglion has moved away from the infundibular ganglion, 

 with which it is joined by a slender externally visible connective. 



In tills same series, the separation of the so-called upper buccal ganglion from 

 the cerebral ganglion also takes place, the buccal remaining united to the brachial 

 ganglion by the brachiobuccal connective. 



The parietal ganglia give rise to the two large pallial nerves. Each of these runs 

 backward and upward, and enters the stellate ganglion on the inner surface of the 



