Of the snake called scitalis The snake called scitalis gets its name because it glitters with such a variety of colour on its back that it slows down those who look at it on account of its markings. And because it is not a keen crawler and cannot overtake the prey it pursues, it catches those who are stunned by the marvel of its appearance. It gets so hot that even in winter it casts off its burning skin, something to Lucan refers: The scitalis alone can shed its skin while the rime is still scattered over the ground’ (Pharsalia, 9, 717).
Of the anphivena The anphivena is so called because it has two heads, one where its head should be, the other on its tail; it moves quickly in the direction of either of its head, with its body forming a circle. Alone among snakes it faces the cold and is the first to come out of hibernation. Lucan, again, says of it: ‘The fell amphisbaena, that moves towards each of its two heads’ (Pharsalia, 9, 719). Its eyes glow like lamps.
Of the ydrus A creature lives in the River Nile which is called idrus, because it lives in water. For the Greek word for water is idros Thus it is called aquatilis serpens, ‘water-snake’. Those who are bitten by it swell up, a sickness called by some boa, because it can be cured by the dung of an ox, bos. The idra is a dragon with many heads of the kind that lived on the island, or marsh, of Lerna in the province of Arcadia. It is called in Latin excedra because when one of its heads is cut off, three grow in its place. This is a myth, however, for it is accepted that the hydra was a place where water gushed out, destroying the town nearby; where, as one outlet was closed up, many others burst open. Seeing this, Hercules drained the marsh and so closed the water-spouts. For the word idra is so called from the Greek word for water.
The idrus is a worthy enemy of the crocodile and has this characteristic and habit: when it sees a crocodile sleeping on the shore, it enters the crocodile through its open mouth, rolling itself in mud in order to slide more easily down its throat. The crocodile therefore, instantly swallows the idrus alive. But the idrus, tearing open the crocodile’s intestines, comes out whole and unharmed.
For this reason death and hell are symbolised by the crocodile; their enemy is our Lord Jesus Christ. For taking human flesh, he descended into hell and, tearing open its inner parts, he led forth those who were unjustly held there. He destroyed death itself by rising from the dead, and through the prophet mocks death, saying:’O death, I will be thy plagues; O grave, I will be thy destruction’ (Hosea, 13:14).