THE NAUTILUS AND OTHER CEPHALOPODS. 



The highest group of mollusks belongs 

 to the class Cephalopoda, which signifies 

 head-footed, the name being given to 

 them because the head is surrounded by 

 a circle of eight or ten arms, which act 

 both as arms and feet. Let us take as an 

 example of this class the common squid 

 of the Atlantic coast (Ommastrephes il- 

 lecebrosa), and see how it is formed. The 

 body is long and cylindrical and ends at 

 the tail in a point ; the dorsal side of the 

 tail end has a pair of triangular fins. The 

 body is practically a hollow cylinder or 

 sac which contains the vital organs of the 

 animal. The neck is in many genera fas- 

 tened to this cylinder or mantle by an 

 apparatus which may be likened to a but- 

 ton and button-hole. The head is round- 

 ed, has on either side the larg^e, round 

 eyes, and at the end it is split up into ten 

 arms, two of which are longer than the 

 others and are called the tentacular arms. 

 On the inner side, the arms are provided 

 with two rows of suckers, which are little, 

 rounded cups placed on pedicels or stems 

 and which form a vacuum when they 

 touch an object and so cling to it. The 

 two long arms are expanded and club- 

 shaped at the end, each club being armed 

 with four rows of suckers. Directly in 

 the center of the circle of arms the mouth 

 is placed and is provided with two sharp 

 beaks Hke those of a parrot, only invert- 

 ed. In addition to these organs there is a 

 large siphon or tube on the ventral side, 

 which is really an organ of locomotion, 

 for it expels water from the mantle cavity 

 with great force, thus rapidly sending the 

 animal backward, its usual direction of 

 propulsion. The body has no shell for 

 protection, but in its place there is a long- 

 rod called a pen, which acts as a back- 

 bone to support the body of the animal, 

 although of course not in the same sense 

 as the backbone of vertebrated animals. 

 In some ccphalopods this pen is hard and 

 stiff but in Ommastrephes it is thin and 

 soft. Such is the general form of a ccpha- 

 lop()<l, familiar names of wliicli arc tlic 



Octopus, Squid, Nautilus, Paper-nautilus 

 and Devil-fish. In this class, also, the 

 majority of the shelled species are ex- 

 tinct, only a few living at the present time. 

 The Ammonite is an example of the ex- 

 tinct cephalopods. 



The most familiar member of this class 

 to the layman is the Pearly Nautilus, the 

 shell of which may be found on the man- 

 tel shelf or what-not of very many dwell- 

 ings. The shell of the Nautilus is formed 

 in a spiral and is made up of many cham- 

 bers, all connected by a tube called a si- 

 phuncie, the outer chamber containing 

 the animal and hence called the living 

 chamber. The shell is called the "Pearly 

 Nautilus,'' but the pearly tints cannot be 

 seen until the outer layer — which is yel- 

 lowish-white with brown markings — is 

 taken ofif, when the exquisite, rainbow- 

 like colors may be observed. 



While the shell of Nautilus is well 

 known the animal is very rare in our mu- 

 seums, although the natives of the Fiji 

 Islands, New Hebrides and New Caledo- 

 nia are able to obtain it in large quanti- 

 ties for food and it is highly esteemed by 

 them. During the voyage of H. M. S. 

 Challenger around the world, a living- 

 Nautilus was captured by dredging in 

 some three hundred and twenty fathoms 

 near Mateeka Island, one of the Fiji 

 group. This was placed in a tub and it 

 swam about in a lively manner by eject- 

 ing water from its funnel. The tentacles, 

 of which there are a larger number than 

 in the other cephalopods, were spread out 

 radially, like those of the sea anemone. 

 The Nautilus lives among the coral reefs, 

 at depths varying from three to three 

 hundred fathoms or more. 



The Fijian's method of capturing the 

 Nautilus for food is thus described (Try- 

 on, — Structural and Systematic Conchol- 

 ogy) : "When the water is smooth so that 

 the Ijottoni.at several fathoms'depth,near 

 tlic border (^f the reef, may be distinctly 

 seen, the lishernian in liis little, frail" 

 canoe scrutinizes (he sands and the coral 



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