IV. 9- 113 



But the Cephalopods and the turbinated Testacea have in common 

 an arrangement which stands in contrast with this. For here the 

 two extremities are brought together by a curve, as if one were 

 to berid the straight line marked E until D came close to A. 

 Such, then, is the disposition of the internal parts ; and round 

 these, in the Cephalopods, is placed the sac (in the Poulps alone 

 called a head),^ and, in the Testacea, the turbinated shell which 

 corresponds to the sac. There is, in fact, only this difference 

 between them, that the sac of the Cephalopods is soft while the 

 shell of the Testacea is hard, nature having invested the fleshy 

 parts with this hard coating as a protection to the animal, which 

 from its limited power of locomotion is exposed to considerable 

 risk. In both classes, owing to this arrangement of the internal 

 organs, the excrement is voided near the mouth ; at a point below 

 this orifice in the Cephalopods, and in the Turbinata somewhat 

 on ohe side of it.''^ 



Such then is the explanation of the position of the feet in the 

 Cephalopods, and of the contrast they present to other animals 

 in this matter. The arrangement, however, in the Sepias and the 

 Calamaries is not precisely the same as in the Poulps, owing to 

 the former having no other mode of progression than by swimming, 

 while the latter not only swim but crawl.^ Thus the former have 

 six of their feet above the teeth, and of these six the two outer 

 ones are the biggest ; while the remaining two, which make up 

 the total eight, are below the mouth and are much the biggest 

 of all, just as the hind limbs in quadrupeds are stronger than the 

 fore Hmbs. For it is these lower feet and these ^ hind legs 

 that have to support the weight, and to take the main part in 

 locomotion. And the outer pair of the upper six are bigger than 

 the pair which intervene between them and the uppermost of all, 

 because they have to assist the lowermost pair in their office. 

 In the Poulps, on the other hand, the four central feet are the 

 biggest.^" Again, though the number of feet is the same in all 

 the Cephalopods, namely eight,^^ their length varies in different 

 kinds, being short in the Sepias and the Calamaries, but greater 

 in the Poulps. For in these latter the body with its sac is of 

 small bulk, while in the former it is of considerable size ; and so 

 in the one case nature has used the materials subtracted from 

 the body to give, length to the feet, while in the other she has 

 acted in precisely the opposite way, and has given to the growth 

 685 a. 8 



