Sequel to the story 'Jimmy Olsen's Private Monster' in Superman's Pal, Jimmy Olsen (DC, 1954 series) #43.
This story was originally a Foley of the Fighting Fifth feature. The features of the lead character have been redrawn as Hopalong Cassidy.
One page puzzzle. Other printings of this story include: Three Mouseketeers, The (DC, 1970 series) #5 (February 1971). The other printings have been identified by the same title and feature name only, and could be wrong.