Connection and Locomotion. 529 
And mounted up and glided down the billow 
In happy freedom, pleased to feel the air, 
And wander in the luxury of light.” * 
Such is the uniform account handed down to us by natu- 
ralists and poets from a very early period; nor need you 
scruple to adopt the wonderful tale. It is true that ‘ there 
are not wanting plain matter-of-fact naturalists who deny that 
the animal saz/s at all +;” but this unbelief savours of over- 
scepticism, or has perhaps no better foundation than a verbal 
quibble. The story is told by several, who appear to have 
been eye-witnesses of the fact ¢, and it is, in every particular, 
conformable to the structure of the creature. It has six ten- 
tacula tapered to a point, and it has two with a dilated mem- 
brane at their tips; and does it seem improbable, as authors 
tell us, that these are held in different attitudes, and are fitted 
for different purposes, while the cuttle pursues its vagrant 
course? Literally, though the contrary has not been proved, 
the breeze may not fill the sails and become the moving 
power; yet to say that the parasite of the Argonatta sails is 
scarcely speaking in a metaphor. 
The Heteropode and Pteropode Mollisca are likewise all 
denizens of the ocean, in whose wide waters they move by 
swimming, or by calmly floating with the current. ‘They 
have no foot wherewith to creep, and they have no arms to 
drag themselves. The former are furnished with fins, variable 
in number and position according to the species; in the latter 
they are always two, one being situated on each side of the 
head. By an undulatory or flapping motion of these organs, 
they move on at a slow rate, and in a reversed position, some 
in their progress alternately dipping below, and reascending to 
the surface. The whole of them, indeed, it is probable, are 
capable of varying the specific gravity of the body at pleasure, 
so as to rise or sink in the water as circumstances may require. 
In calm weather, they will frequently ascend and float on the 
surface in immense shoals, as is the case with the Clio borealis 
and Limacina helicialis of the Arctic seas ; little snails which 
I should have introduced to your notice earlier, as furnishing 
the whale a great part of its sustenance. In swimming 
. . . . o? 
according to the intelligent navigator Scoresby, the Clio 
* Montgomery’s Pelican Island, canto i. 
Zool. Journal, iv. 58. : 
In his Account of an Expedition to Surinam (vol. i. p. 11.), Stedman has 
given a description of the Argonatta, concerning the accuracy of which I 
would wish to warn the reader. He seems to have observed the Holo- 
thiiria Physalis (which is not a molluscous animal), and mixed up the de- 
scription of it with what he had read or heard of the Argonatta, 
