you want to learn linnaean taxonomy?
"The FROG-FISH, or the metamorphosis is very paradoxical, as Nature
would not admit the change of one Genus into another one of a
different
Class. Rana, as all amphibians, possesses lungs and spiny bones. Spiny
fishes are
provided with gills instead of lungs. Therefore this change would be
contrary to
nature's law. For if this fish is provided with gills, it will be
different from Rana and
the amphibians; if with lungs, it will be a Lizard, for there is all
the world of difference
between them and Chondropterygii and Plagiuri. "
Carl Linnaeus work systema naturae 1735 (translated from latin to english)
from
https://www.kth.se/polopoly_fs/1.19...umn-content/attachment/Linnaeus--extracts.pdf