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A MONOGRAPH 
OF THE 
MOLLUSCA FROM THE EOCENE FORMATIONS 
OF ENGLAND. 
FIRST CLASS—CHPHALOPODA. CvuviEr. 
Mo.uvusca BracuiaTa. Poli. 
Cfpuatoropes. Lamarck; Férussac. 
CépHatopHores. De Blainville. 
THE Cephalopoda form the first class of Molluscous Animals in the system 
proposed by Cuvier, and consist of the several encephalous mollusca whose organs of 
reptation are attached to the head. Possessing an organization more complicated 
and more fully developed than that of the other molluscs, they have a higher rank 
in the scale of existence. In a descending series they immediately succeed the 
Vertebrata. 
It is in this class that the latest indication of an internal skeleton will be found. 
Among the more highly organized of the Cephalopods, the cephalic ganglia, to which, 
from their importance and development, the term drain may still be applied, are 
surrounded and protected by a cartilaginous process, called the cranial cartilage, 
analogous with the cranium of a vertebrate animal, and in which the muscles of the 
arms and tentacula are inserted. Other cartilages, subservient to the muscles of the 
funnel and of the fins, where those organs exist, will be found in other parts of the 
body, and may be said to represent, in rudiment, those portions of the skeleton which 
in the vertebrate animals sustain their locomotive organs. 
The Cephalopods are eminently social animals; they are all predatory and 
voracious in the extreme, and appear to be nocturnal or crepuscular in their habits. 
Some, the more highly organized, inhabit the deep seas only; others frequent the 
coasts or shallow seas, or conceal themselves in holes in the rocks. M. d’Orbigny, to 
whose recent work entitled ‘Mollusques vivants et fossiles’ I am largely indebted, 
shows that to these various habits the zoological peculiarities of the different genera 
are referable ; and he distinguishes the animals as pelagic (pelagiens), or littoral 
(cOtiers), according to the fact of their frequenting the deep sea or the coasts. 
The Cephalopoda have a distinct head, surrounded by arms or tentacula; they 
possess organs of sight and hearing, closely resembling those of vertebrate animals, 
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