The Brown Fox Mystery. The White Elephant Mystery. The Yellow Cat Mystery. The Blue Herring Mystery. Textured composition binding, orange with black lettering.
Front cover carries a small picture of the title animal in black.
Textured composition binding, light tan, light gray or tan-gray. Undecorated or with a small picture of the title animal on front cover. It appears that the Grosset and Dunlap editions had the same illustrations as the earlier editions. Different picture for each book. This juvenile mystery series was created by the team of Dannay and Lee, famous for the adult mysteries written under their Ellery Queen pseudonym.