Oops - my bad.
When I wrote the last post this morning I was multitasking, glanced quickly at the pictures, didn't think too hard on what I was typing, and got it totally wrong.
The mount shown is, of course, a Standard mount, not a B-mount.
The standard mount was Arri's first interchangable mount.
The B-mount was a later introduction (60's?) to solve some of problems with the B mount (soft materials, poor rotational indexing, poor seating repeatability).
The B mount was superseded by the PL mount.
Many Ang. lenses, like this one, had a tail end configured to take multiple, interchangable (with colimation) mounts.
The rest of the post should be accurate. Both the B and Std mount had a 52mm backfocus, so this lens could, in theory, mount onto an EOS with a backfocus of 42mm, provided it could clear the mirror box inset, but I've never seen such an adapter.
The lens would probably have marginal coverage at the wide end.