Pliny the Elder [1st century CE] (Natural History, Book 9, 72; 32, 20): [Book 9, 72] Nor are there wanting dire poisons, as in the sea-hare which in the Indian Ocean infects even by its touch, immediately causing vomiting and laxity of the stomach, and in our own seas the shapeless lump resembling a hare in color only, whereas the Indian variety is also like a hare in size and in fur, only its fur is harder; and there it is never taken alive. [Book 32, 20] The poison of the sea-hare is counteracted by the sea-horse taken in drink. - [Rackham translation]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 6:23): The sea-hare [epus] is named for the similarity of its head to that of a hare. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.48; 7.49): [Fish 7.48] The sea-hare is very poisonous, as Pliny says. In the Indian sea it is so noxious that when touched it immediately causes vomiting and disintegration of the stomach; but in our seas it is shapeless, the color of a hare, similar in size to a terrestrial hare, but with harder fur. The enemy of this fish and others is a most pestilential stingray [pastinaca, literally "sea parsnip"], which pierces them as if with an evil poisoned sword. The fishes fleeing, lest they be struck by the sting, fasten themselves to the roots of trees. But if any one is bitten by the same fish, its ashes are a remedy. [Fish 7.49] The sea-hare is also a different kind of marine fish, as Pliny and Isidore say, which has its name from the fact that it has a head like a terrestrial hare; the rest of the body is a fish. - [Badke translation/paraphrase]