THE NAUTILUS AND OTHER CEPHALOPODS. 



The highest group of mollusks belongs Octopus, Squid, Nautilus, Paper-nautilus 



to the class Cephalopoda, which signifies and Devil-fish. In this class, also, the 



head-footed, the name being given to majority of the shelled species are ex- 



them because the head is surrounded by tinct, only a few living at the present time, 



a circle of eight or ten arms-, which act The Ammonite is an example of the ex- 



both as arms and feet. Let us take as an tinct cephalopods. 



example of this class the common squid The most familiar member of this class 

 of the Atlantic coast (Ommastrephes il- to the layman is the Pearly Nautilus, the 

 lecebrosa), and see how it is formed. The shell of which may be found on the man- 

 body is long and cylindrical and ends at tel shelf or what-not of very many dwell- 

 the tail in a point; the dorsal side of the ings. The shell of the Nautilus is formed 

 tail end has a pair of triangular fins. The in a spiral and is made up of many cham- 

 body is practically a hollow cylinder or bers, all connected by a tube called a si- 

 sac which contains the vital organs of the phuncle, the outer chamber containing 

 animal. The neck is in many genera fas- the animal and hence called the living 

 tened to this cylinder or mantle by an chamber. The shell is called the "Pearly 

 apparatus which may be likened to a but- Nautilus," but the pearly tints cannot be 

 ton and button-hole. The head is round- seen until the outer layer which is yel- 

 ed, has on either side the large, round lowish-white with brown markings is 

 eyes, and at the end it is split up into ten taken off, when the exquisite, rainbow- 

 arms, two of which are longer than the like colors may be observed. 

 others and are called the tentacular arms. While the shell of Nautilus is well 

 On the inner side, the arms are provided known the animal is very rare in our mu- 

 with two rows of suckers, which are little, seums, although the natives of the Fiji 

 rounded cups placed on pedicels or stems Islands, New Hebrides and New Caledo- 

 and which form a vacuum when they nia are able to obtain it in large quanti- 

 touch an object and so cling to it. The ties for food and it is highly esteemed by 

 two long arms are expanded and club- them. During the voyage of H. M. S. 

 shaped at the end, each club being armed Challenger around the world, a living 

 with four rows of suckers. Directly in Nautilus was captured by dredging in 

 the center of the circle of arms the mouth some three hundred and twenty fathoms 

 is placed and is provided with two sharp near Mateeka Island, one of the Fiji 

 beaks like those of a parrot, only invert- group. This was placed in a tub and it 

 ed. In addition to these organs there is a swam about in a lively manner by eject- 

 large siphon or tube on the ventral side, ing water from its funnel. The tentacles,, 

 which is really an organ of locomotion, of which there are a larger number than 

 for it expels water from the mantle cavity in the other cephalopods, were spread out 

 with great force, thus rapidly sending the radially, like those of the sea anemone, 

 animal backward, its usual direction of The Nautilus lives among the coral reefs,, 

 propulsion. The body has no shell for at depths varying from three to three 

 protection, but in its place there is a long hundred fathoms or more, 

 rod called a pen, which acts as a back- The Fijian's method of capturing the 

 bone to support the bodry of the animal, Nautilus for food is thus described (Try- 

 although of course not in the same sense on, Structural and Systematic Conchol- 

 as the backbone of vertebrated animals, ogy) : "When the water is smooth so that 

 In some cephalopods this pen is hard and the bottom, at several fathoms' depth, near 

 stiff but in Ommastrephes it is thin and the border of the reef, may be distinctly 

 soft. Such is 1 the general form of a cepha- seen, the fisherman in his little, frail' 

 lopod, familiar names of which are the canoe scrutinizes the sands and the coral. 



