Connection and Locomotion. 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 1S 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 progréssion, 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 Mollisca, 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 * 
with perhaps little less agility. Lamarck, indeed, denies this, 
and says that these can only trail seclacs 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 +; 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- 
* Plist. Nat. des An. sans Vert., vu. 583. and 656. 
+ Cuvier’s Mémoires, 1. p. 3. 
MM 4 
