I found a picture of the one with the ball on a 1988 Logitech poster. The one on the right was made by Hawley. It sports the triple-circle mouse head Hawley logo with the cross-hairs in the middle.
Notice that the Hawley mouse has two wheeled feet instead of a ball to move the cursor. These wheels are nearly parallel with the bottom. These are still unique in the closeup and scan of the inside. >
The Hawley digital mouse comes apart if three plastic tabs are pushed in. It took a very sturdy plastic knife and a couple of thin things to hold it open while each next tab was forced in. I just had to look at the inside. >