148 ON THE METHOD OF ZADIG. 



chamber with the largest. There is nothing like this 

 in the vegetable world ; but an exactly corresponding 

 structure is met with in the shells of two kinds of exist- 

 ing animals, the pearly Nautilus and the Spirula, and 

 only in them. These animals belong to the same di- 

 vision the Cephalopoda as the cuttle-fish, the squid, and 

 the octopus. But they are the only existing members 

 of the group which possess chambered, siphunculated 

 shells; and it is utterly impossible to trace any physio- 

 logical connection between the very peculiar structural 

 characters of a cephalopod and the presence of a cham- 

 bered shell. In fact, the squid has, instead of any such 

 shell, a horny "pen," the cuttle-fish has the so-called 

 "cuttle -bone," and the octopus has no shell, or, at 

 most, a mere rudiment of one. 



Nevertheless, seeing that there is nothing in nature 

 at all like the chambered shell of the Belemnite, except 

 the shells of the Nautilus and of the Spirula, it was 

 legitimate to prophesy that the animal from which the 

 fossil proceeded must have belonged to the group of the 

 Cephalopoda. Nautilus and Spirula are both very rare 

 animals, but the progress of investigation brought to 

 light the singular fact, that, though each has the charac- 

 teristic cephalopodous organisation, it is very different 

 from the other. The shell of Nautilus is external, that 

 of Spirula internal; Nautilus has four gills, Spirula 

 two ; Nautilus has multitudinous tentacles, Spirula has 

 only ten arms beset with horny rimmed suckers ; Spirula, 

 like the squids and cuttle-fishes, which it closely re- 



