In cases of hydrophobia resulting from the bite of the mad dog, the practice is to rub the patient’s face with the fat of the sea-calf; an application rendered still more efficacious by the admixture of hyæna’s marrow, oil of mastich, and wax. Bites inflicted by the muræna are cured by an application of the head of that fish, reduced to ashes. The pastinaca,[149] also, is remedial for its own bite, the ashes of the same fish, or of another of the same genus, being applied to the wound with vinegar. When this fish is intended for food, every portion of the back that is of a saffron colour should be removed, as well as the whole of the head: care, too, should be taken not to wash it over much; an observation equally applicable to all kinds of shell-fish, when intended for food, the flavour being deteriorated[150] thereby. The hippocampus,[151] taken in drink, neutralizes the poison of the sea-hare. As a counter-poison to dorycnium,[152] sea-urchins are remarkably useful; as also in cases where persons have taken juice of carpathum[153] internally; more particularly if the urchins are used with the liquor in which they are boiled. Boiled sea-crabs, too, are looked upon as highly efficacious in cases of poisoning by dorycnium; and as a neutralizer of the venom of the sea-hare they are particularly good. CHAP. 21. (6.)—THE VARIOUS KINDS OF OYSTERS: FIFTY-EIGHT REMEDIES AND OBSERVATIONS. PURPLES: NINE REMEDIES. Oysters, too, neutralize the venom of the sea-hare—and now that we are speaking of oysters, it may possibly be thought that I have not treated of this subject at sufficient length in the former part[154] of my work, seeing that for this long time past the palm has been awarded to them at our tables as a most exquisite dish. Oysters love fresh water and spots[155] where numerous rivers discharge themselves into the sea; hence it is that the pelagia[156] are of such small size and so few in number. Still, however, we do find them breeding among rocks and in places far remote from the contact of fresh water, as in the neighbourhood of Grynium[157] and of Myrina,[158] for example. Generally speaking, they increase in size with the increase of the moon, as already stated by us when[159] treating of the aquatic animals: but it is at the beginning of summer, more particularly, and when the rays of the sun penetrate the shallow waters, that they are swollen with an abundance of milk.[160] This, too, would appear to be the reason why they are so small when found out at sea; the opacity of the water tending to arrest their growth, and the moping consequent thereon producing a comparative indisposition for food.