leton of the prothorax to the bones of the
cerebellum, of the palate, and the pieces of the larynx, the skeleton of
the mesothorax to the parietals, interparietals, and opercular bones,
and that of the metathorax to the skeleton of the thorax of Vertebrates.
The pieces of the abdomen and of the terminal segment correspond to the
bones of the abdomen and coccyx (p. 458). It does not need the
subsequent likening of the hind wings of insects to the air bladder of
fish, and of the stigmata to the pores of the lateral line, to convince
one finally of the fancifulness of the whole comparison.

In 1830 two young naturalists, Meyranx and Laurencet, presented to the
Academie des Sciences a memoir in which they likened a Cephalopod to a
Vertebrate bent back at the level of the umbilicus, saying that the
Vertebrate in this position had all its organs in the same order as in
the Cephalopod. Geoffroy took up this idea with enthusiasm, seeing in it
a further application of his master-idea of the unity of plan and
composition. By means of this comparison Mollusca definitely took their
place in the _Echelle des etres_, after the Articulata, just as Geoffroy
had maintained in 1820, saying that crabs formed a link between the
other Crustacea and the molluscs.[94] The comparison brought him nearer
to the end he had in view, the reference of all animal structure to one
single type.

But in championing the memoir of Meyranx and Laurencet, Geoffroy found
himself in direct antagonism with Cuvier, who held that his four
"Embranchements" had each a separate and distinct plan of structure. In
a paper read to the Academy in February 1830,[95] Cuvier easily
demolished the crude comparison of the Cephalopod to the Vertebrate. He
gave diagrams of the internal organs of a Cephalopod and of a Vertebrate
bent back in the manner indicated by Meyranx and Laurencet, and he
showed in detail that the arrangement of the main organs was quite
different, that the likeness would have been much greater if the
Cephalopod had been likened to a Vertebrate doubled up the other way,[96]
but that even then the arrangement of the organs would not be the same.
The organs, too, of the Cephalopod are differently constructed. He sums
up his criticism by saying:--"I give true and summary expression to all
these facts when I say that Cephalopods have several organs in common
with Vertebrates, which fulfil in either case similar functions, but
that these organs are different