What Rough Bestiary: Agricola's De Animantibus Subterraneis

Patrick Stuart is the one to blame for invoking it, and Humza Kazmi for completing the summoning, on G+ recently. So now we have Georgius Agricola's underground monster manual for entertainment.

Basilisk vs. weasel

There is the usual medieval bestiary nonsense about how bears lick their cubs into shape because Ovid said so, foxes fish with their tails, weasels kill basilisks, and also some choice bits:

Killer hamster: "It seems angry and caustic to a degree that if an unprotected horseman were to pursue it, it is accustomed to leap up and seize on the face of the horse, and if someone were to capture it, it is accustomed to hold on by biting." [109]

Haemorrhoid snake: unfortunate name for "a snake whose bite was said to cause bleeding from all over the body" [117]

Fire toad: "On the other hand, the poisonous frog, which our miners call by their own word puriphrunos (fire toad) because of the color of fire which is on it, hides continuously among rocks as if buried and interred... In this way they appear in solid rocks, although there are no holes to be seen." [119]

Six types of demons: "In fact, Psellus, when he classified the number of demons into six types, says that this kind is worse than the others, because the material of its skin is thicker." [121] (Psellus' classification, found here, is into Igneous, Aerial, Earthly, Aqueous, Subterranean and Lucifugus - a whole topic unto itself.)

Hobgoblins: "For they passionately ridicule joy; and they seem to do many things, but do nothing completely." They appear as old men clad in the manner of miners, 3/4 as tall as a dwarf, and were enslaved by the Swedish. [121-122]

The use of these creatures is left as an exercise to the reader.