112 iv, 8 — iv. 9. 



but they have them in this irregular way, owing to imperfect 

 formation and to their not using them for their natural purpose, 

 but for locomotion. 



For a detailed account of the several parts of these animals, of 

 their position, and their differences, those parts being also included 

 which distinguish the sexes, reference must be made to the 

 treatises on Anatomy and to the Researches concerning Animals. 



(Ch. g.) We come now to the Cephalopods.^ Their internal 

 organs have been already described with those of other animals. ^ 

 Externally there is an uniform sac inclosing the body ; and in 

 front of this sac a head surrounded by feet, which form a circle 

 about the mouth and teeth, and are set between these and the 

 eyes. Now in all other animals the feet, if there are any, are 

 placed in one of two ways ; either before and behind, or along 

 the sides, the latter being the method adopted in those bloodless 

 animals whose feet are numerous. But in the Cephalopods there 

 is a peculiar arrangement, distinct from either of these. For their 

 feet are all placed at what may be called the fore end. The reason 

 for this is that the hind and fore parts of their body have been 

 drawn up close to each other, ^ as is also the case in the turbinated 

 Testacea. For these latter, while in some points they resemble 

 the Crustacea, in others resemble the Cephalopods. Their earthy 

 matter is on the outside, and their fleshy substance within. So 

 far they are like the Crustacea. But the general plan of their 

 body is that of the Cephalopods ; and, though this is true in a 

 certain degree of all the Testacea, it is more especially true of 

 those turbinated species, that have a spiral shell.* This general 

 plan, common to the two, is as follows. Let us first consider 

 the case of quadrupeds and of man, where the arrangement is 

 that of a straight line. At the upper end of this line, A represents 

 the mouth, then B the gullet, and C the stomach. After this 

 comes the intestine reaching to the vent, which is marked by DJ^ 

 Such is. the plan in sanguineous animals ; and round this straight 

 line as an axis are disposed the head and trunk ; the remaining 

 parts, such as the anterior and posterior limbs, having been super- 

 added by nature, merely to minister to these and for locomotion. 



Now in Crustacea and in Insects there is a tendency to a similar 

 arrangement of the internal parts in a straight line ; the distinc- 

 tions between these groups and the sanguineous animals depending 

 on differences of the external organs which minister to locomotion. 

 684b. 



