But if we embrace this view, we must not forget that there are living Cephalopoda, such as the Octopods, which are devoid of any hard parts, whether external or internal, and which could leave behind them no fossil memorials of their existence, so that we must make a somewhat arbitrary assumption, namely, that at a remote era, no such dibranchiata were in being, in order to avail ourselves of this argument in favour of progression.
"The Antiquity of Man"
Charles Lyell