Turns out I have two such lenses.
One is attached to a JVC KY27 Betacam, and it is the J8x6B, 6-48mm, pictured here.

Here’s a shot of the mounting hardware on lens and JVC.

The other lens is a J13x9B4, 9-117mm (ah!, there’s an instance of a 4 after the B). It has a 2x extender on it, for what that’s worth. Also engraved on it are the words “Canon Macro TV zoom”, which I presume means it’s got macro focusing capability.

Here’s a shot of its mount.

I’d swear I read somewhere about using a MFT-to-Nikon lens adapter for these Canons, but the bayonet cutouts in my $20 K&F Concept adapter for Nikon G lenses are much shallower than what is required by the Canons. Maybe machining was involved, or maybe I misread.
I welcome all comments about these lenses and the feasibility of using them with a Panasonic GH4 micro-four-thirds camera.
If it is feasible, has anyone found a way to provide power to the zoom? (I realize I can probably find pinouts for the connector by searching, but an existing recipe is always preferable.)
Thank you, again!