is BRITISH MARINE TESTACEOUS MOLLUSCA : 
Sixth Division. 
CEPHALOPODA DIBRANCHIATA. 
Bisexual. 
These singular and highly organized animals are distributed 
in two families: the Octopodide include the genera Eledona 
and Octopus; the Decapodide, Loligo, Sepia, Sepiola and 
Spirula: they all creep and swim. They are elaborately and 
anatomically described and illustrated by M. Cuvier in his 
memoirs, and by Professor Owen in the second part of the 
second volume of the ‘ Zoological Transactions.’ We have 
merely mentioned these animals to preserve intact the chain 
of the synopsis. To attempt to add novelty to this almost 
exhausted subject would be a vain and fruitless labour. 
This is a most aberrant group, and cannot be placed in 
line; they are the most advanced in composition of the yet 
discovered undoubted Mollusca; but there appears so large 
an hiatus between them and the class they terminate, that 
they can only be considered an anomalous lateral branch. 
I have now finished a limited analysis of my method of the 
distribution of the British marine testaceous Mollusca. I am 
led to think the sexual arrangement natural and well-founded, 
as it cannot fail to have been observed that as the generative 
influences are more or less perfect, there is a corresponding 
energy and activity. If we cast a glance at the strict herm- 
aphrodites, as the Acephala and Patella tribes, we find them 
either fixed or of the most limited locomotion ; but as soon as 
the generative structure is improved, the animals become 
more lively and locomotive. This view is exemplified in the 
hermaphrodites with congression, for instance, in the natatory 
Gasteropoda and Pulmonifera; but when bisexuality is esta- 
blished, there is an evident increase of motion, functions, and, 
I may say, even of intelligence and structural composition. 
And lastly, on arriving at the most highly developed genera- 
tive influences that can attach,to the Invertebrata, we see an 
energy and activity that even exceed those qualities i some 
