XII 



PHYLUM MOLLU8CA 



740 



cerebral) are connected by slender connectives with a pair of 

 stomatogastric ganglia (Fig. 669, g. stom.), also closely united, situated 

 on the posterior aspect of the oesophagus. Besides the ten brachial 

 nerves, each of which, expanding at the base of the arm into a 

 brachial ganglion, runs along the axis of the arm to its extremity, 

 the pedal ganglia also give off nerves to the funnel, and also a 

 pair to the statocysts ; but the latter are found, when their fibres 

 are traced to their origin, to be derived from the cerebral ganglia. 

 The pleuro-visceral ganglia give off two visceral nerves (Fig. 676, 

 vise, n.) supplying the various internal organs, one pair of branches, 

 the branchials, having each a branchial ganglion at the base of the 



scl.carl 



corn, 



set- c Ctrl 



orb.ccL.rt 



FKJ. 677. Sepia, section of eye. cil. proc. ciliary processes ; corn, false cornea ; ir. iris ; Jens, 

 lens ; opt. g. optic ganglion ; orb. cart, orbital cartilage ; rds. rods ; ret. retina ; scl. cart. 

 sclerotic cartilage. (From Vogt and Jung, after Hensen.) 



ctenidium, and running along its axis to its extremity. Two other 

 ganglia of considerable size the visceral and the gastric occur in 

 the course of this system. The pleuro-visceral ganglia also give 

 off two very stout pallial nerves (pall, n.) which run through the 

 neck to the inner surface of the mantle-cavity, where each expands 

 into a large, flat, pallial or stellate ganglion (Fig. 667, I. st. g.}, which 

 is visible in front of the ctenidium when the mantle-cavity is opened. 

 From the outer edge of this arise a number of nerves supplying the 

 various parts of the mantle. 



The organs of special sense of the Cuttle-fish are much more 

 highly developed than those of Triton. The eyes (Fig. 677) are 



VOL. i 3 it 



