Subtitled "Volume I - Aerth Animalia and Unique Flora", but planned future volumes were never printed.
From the back cover:
Betuhuru? Horntooth? Hippocorn? Blindworm? Green Racer? Strange names for strange creatures... these beasts and hundreds more await you inside the Mythus Bestiary. Prepared especially for use with the Mythus fantasy roleplaying system, the Mythus Bestiary is an encyclopedic reference containing descriptions of over 400 creatures - some animal, some vegetable, some mineral.
The listings inside the Mythus Bestiary are divided into separate treatments of Exterior Aerth, Interior Aerth, and Subterranean Aerth for ease of reference.
A bull the size of an elephant? A scorpion the size of a bull? An elephant the size of a pony? A lizard that could eat a tiger? A tiger with 9-inch fangs? The Mythus Bestiary is more than just a list, however. Each creature is fully detailed and illustrated, from the bovine aurochs (5 feet at the shoulder) and teh Atlantean pygmy elephant of the Exterior, to the Dilophosaurus (a poison-spitting carnivorous dinosaur) and the fin-backed dragon of the Interior. Denizens of the briny deep are not neglected; a sea voyage might be cut short by anything from the lowly barracuda and the great white shark to the sea mugger (a giant oceanic crocodile), the serpent whale, or the true sea serpent (as its name implies, there are several such monsters). There is more to Aerth than just the two worlds on the inside and outside, however. The Mythus Bestiary also deals with the strange creatures inhabiting the dank caves and stygian passages of Subterranean Aerth: cave apes, centaurants, smotherslugs, drownweed and other nightmare monsters.
Reptile Men? Intelligent Foxes? Walking Mushrooms? Living Rocks? In addition to the "dumb animals" noted above, the Mythus Bestiary also includes many tribes of humanoids: primitive cave-dwellers, savage lizard-men, flying bat-people... the list goes on and on.
The world of Aerth can be a dangerous place for the unwary. The Mythus Bestiary will help prepare you for your journey.