Connection and Locomotiori, 527 



necessary, previously to entering on the details, to make a 

 remark or two on the general structure of the moving powers. 

 Like the muscles of superior animals, these are composed of 

 parallel fibres, but of a bluish-white colour, soft and jelly- 

 like, and rather loosely connected ; for the cellular substance, 

 which binds together those of red-blooded animals, is here 

 very generally wanting. They have, apparently, no tendons, 

 but this is, according to Cuvier, owing to the colour being 

 the same in the tendinous and the fleshy parts. The fibres 

 are, in general, closely and inextricably interlaced, the inser* 

 tions being lost in one another, or in the skin under which 

 they lie, and from which, indeed, it seems impossible to sepa- 

 rate them by any definite line. Chemically they consist of 

 fibrine, but the medium which cements them to the shell 

 appears to be gelatinous, for it is loosened and detached by 

 maceration and boiling, operations which have an opposite 

 effect, on fibrine. 



Molluscous animals are either erratic or permanently sta- 

 tionary. The former, according to the different modes of 

 their progression, may be distributed into three classes ; viz. 

 those which swim, those which creep in an even continuous 

 manner, and those which drag themselves forward at inter- 

 rupted intervals. 



The Cephalopodous Mollusca, or cuttle-fish, belong to the 

 first class. These singular animals swim at freedom in the 

 bosom of the sea, moving by sudden and irregular jerks, the 

 body being nearly in a perpendicular position, and the head 

 directed downwards and backwards. Some species have a 

 fleshy muscular fin on each side, by the aid of which they 

 accomplish these apparently inconvenient motions ; but at 

 least an equal number of them are finless, and yet can swim 

 w ith perhaps little less agility. Lamarck, indeed, denies this, 

 and says that these can only trail themselves along the bot- 

 tom by means of the suckers, which are so beautifully arranged 

 along the internal edge of their tentacular arms.* This is 

 probably their usual mode of proceeding; that it is not their 

 only one, we have the positive affirmation of other observers. 

 Thus Cuvier tells us that the Octopi are excellent swimmers, 

 and move in the water with rapidity f ; and Dr. Grant, when 

 describing an individual of the same genus which he had pre- 

 served in sea-water, says, " The animal swam several times 

 hurriedly across the basin, always with its posterior extremity 

 forward, by repeatedly striking forward, the whole of its web- 



* Hist. Nat. des An. sans Vert., vii. 583. and 656. 

 f Cuvier's Memoires, i. p. 3. 



MM 4 



