390 



MOLLUSC A. 



mb 



FIG. 390. Anatomy of Octopus vulgar is. a, amis; ao, aorta; cv, vena cava with ne- 

 phridial appendage ; d, intestine ; go, optic ganglion ; /<, systemic heart ; e, crop ; 

 K, head ; A-, ctenidia ; fc/t, branchial heart ; fcn, cartilage; I, I', liver and gall duct, 

 the liver indicated by dotted line; M, mantle; o, ovary; od, oviduct; p, pedal 

 ganglion ; s, buccal mass with salivary glands; s<, stellate ganglion ; s.y, stomach 

 and sympathetic ganglion ; 7', basis of tentacles ; t, ink sac ; u, visceral ganglion ; 

 vfc, auricle of systemic heart ; *, spiral blind sac. 



glia of the nervous system (fig. 391). A 

 single dorsal mass represents the cerebral 

 ganglia; connected with this by broad com- 

 missures, the pedal and visceral (viscero- 

 pleuro-parietal) ganglia lie close together 

 ventrally. With these parts are associated 

 upper and lower buccal ganglia. The large 

 optic ganglia, developed in the optic nerve 

 arising from the cerebrum, are especially 

 characteristic of the Cephalopoda, as are the 

 ganglia stellata, right and left at the anterior 

 edge of the mantle (fig. 390), which owe 

 their name to the radiation of fibres to inner- 

 vate the mantle. An unpaired sympathetic 

 ganglion lies at the junction of stomach and 

 blind sac. Cerebral, pedal, visceral and optic 

 ganglia are enclosed in the cephalic cartilage, 



FIG. 391. Nervous system 

 of Sepia officinalis from 

 the side, obi, inferior 

 buccal ganglion ; gbs, su- 

 perior buccal ganglion ; 

 0c, cerebral ganglion ; grp, 

 pedal ganglion ; 0u, vis- 

 ceral ganglion ; rnib, buc- 

 cal mass; ce, oesophagus ; 

 op, optic ganglion. 



