That is exactly what I tried doing but their PDF versions do not exist. Incidentally, you are spot on. I am editing my translation of The Origin.

The link provided below gave me the following response. I think it is correct.

Since the topic is Consciousness in humans, I would say that "headed behavior" refers to the behavior of humans as a result of the things we think, our conscious decisions, the impulses within our head.

https://forum ...

Could it be "the behavior of living beings that have a head?"

"And what a truly vigorous and exciting program of research it was! with its gleaming stainless-steel promise of reducing all conduct to a handful of reflexes and conditional responses developed from them, of generalizing the spinal reflex terminology of stimulus and response and reinforcement to ...

It pops up here (The Double Brain), too.
"Language, that most urgent and significant of skills, the pre-emptory and exigent ground of social action, the last communicant thread on which life itself in the post-glacial millennia must often have depended!"(Italics mine)
Here is how Merriam Webster ...

Native speakers, please!

From The Intellectual Consciousness of Greece in The Origin of Consciousness
... the response of Achilles begins in his etor, or what I suggest is a cramp in his guts, where he is in conflict or put into two parts (mermerizo) whether to obey his thumosy the immediate internal sensations of anger ...