VI.] ON THE METHOD OF ZADIG. 141 



animals belong to the same division 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 physiological connec- 

 tion between the very peculiar structural characters of 

 a cephalopod and the presence of a chambered 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 investiga- 

 tion brought to light the singular fact, that, though 

 each has the characteristic cephalopodous organisation, 

 it is very different from the other. The shell of Nauti- 

 lus 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 resembles, has a bag of ink 

 which it squirts out to cover its retreat when alarmed ; 

 Nautilus has none. 



No amount of physiological reasoning could enable 

 any one to say whether the animal which fabricated 

 the Belemnite was more like Nautilus, or more like 



