IT is by no means obvious what may have been meant by "imperfect creatures," or in what sense desire, unless it be as instinct, can be assigned to them; for there is no trace throughout the zoology of
Aristotle, extensive as it is, of any such species of being. One commentator has suggested polypi and mollusca; but the former, in their present acceptation, (improperly termed zoophytes), had not then
been observed, and the latter could not, from the description, have been regarded as "imperfect animals." The "polypus" was the generic term for the highest forms of the Cephalopoda, or " cuttle fish."