Was it designed to plug into the Parallel port or a special female serial/bus port?

I think BOxley may have been on to something in the old EzBoard forums. If it is a serial mouse, you could get an adapter. The guys at a local shop named "Computer Linc" used to call it a 9 pin "daddy". I flunked their tech-test because I called it a serial port adapter instead of a "daddy". Apparently when I learned computer hardware I did so by reading manuals and learning the proper terms for things, and not by assigning slang to them and futzing around to figure out how they worked. So you'll most likely need a 25 pin "mommy" to 9 pin "mommy"? I guess the "daddy" part is male, and the "mommy" part is female? Most modern motherboards have a 9 pin "daddy" connector, the older ones have the 25 pin "daddy" connector. It looks like, from the photo, that it needs a 25 pin "mommy" port. It appears to be only using a few pins on the "daddy" part.

It almost looks like an Amiga 1000 serial port, on which the gender was reversed? Good thing they fixed that with the Amiga 500 and Amiga 2000, to use almost the same serial ports as the IBM PC systems.