go 



Part second. 



animal after them. Tne Octopus only swims when escaping from 

 some danger or when pouncing on a swimming prey. The swimming 

 movement is brought about by the violent ejection of water from 

 the mantle-cavity through the funnel, the arms being at the same 

 time extended forwards (fig. 72). The back-kick thus produced 

 drives the animal rapidly through the water, the hind end of the 

 body first. Food consists chiefly of crabs, which, after being caught 

 and carried to the mouth by means of the arms, are quickly par- 

 alyzed by a poisonous fluid secreted by the sal vary glands. Then 

 the juices are sucked ont of the body, the solid parts not being swal- 

 lowed. Mussels are also eaten by the Octopods. They shove 

 a stone between the gaping valves of the mussel-shell to prevent 

 their closure and then suck out the soft parts. They lie in wait 

 for their victims hidden in crevices in the rocks and in the Aquarium 

 they collect large stones behind which they conceal themselves. 

 Their power of changing their colour and of producing all sorts 

 of warts and wrinkles on their otherwise smooth skin enables 

 them so closely to counterfeit their surroundings, that they can 

 only be distinguished with difficulty. When well fed they grow 

 rapidly in the Aquarium ; in about 81/2 months the weight of one 

 animal rose from 65 to 2400 grammes. Sometimes they suffer 

 from a strange illness which must be considered as a form of 

 psychosis: the animals eat their own arms down to short stumps, 

 at the same time refusing all other nourishment and soon dying. 



Octopods are caught on all shores of the Mediterranean and 

 chiefly in wicker baskets ("Nasse") or in small pots ("Lancelle") 

 into which they crawl, or they are speared. They are common 

 in the fish-markets of Naples, as they are largely eaten, the young 

 examples being especially esteemed. 



A very near ally of Octopus is Eledone moschata, the Musk- 

 octopus, much smaller and with only one row of suckers on each 

 arm. They are very shy and try to hide themselves from view. 

 When taken out of the water they give out a strong odour of musk. 

 As they are quite common they are often brought to market, but 

 are generally only eaten by the common people. 



One of the most interesting and most important of the Cepalo- 

 pods is the Sepia or Cuttlefish (Sepia officinalis, fig. yd,). Their 

 body is oval, somewhat flattened, and with a membranous fin 

 running down both sides. Beneath the dorsal skin is the "cuttle- 

 bone", found often on the English coast and given to captive 

 canaries to sharpen their beaks. The eight arms are much shorter 

 than those of the Octopus and are generally carried closely applied 

 together; between them is hidden another much longer pair of 

 arms which can be shot out to catch crabs or fish. 



The most noticeable characters in Sepia are the excretion of 

 an inky fluid and the change of colouring in the skin. Both of 

 these they have in common with the other Cephalopods, but they 



