An interesting study to the lover of nature it is to watch the wonderful movements of these sea reptiles. Swimming and diving with equal facility, flashing into sight and disappearing again in twos or scores, or in large shoals, pursuing fish, many of them of bright colouring, they offer constant amusement to the beholder. Sometimes, when the sailors are throwing their nets, they disappear beneath the waves, and are no longer seen for half an hour or more; when presently, far away from the spot where they vanished so suddenly, up they come to the surface again, to sport once more, or take in a fresh supply of air. Pity they possess such evil qualities to blind us to their beauties, for they rank among the most venomous of serpents. They belong to the sub-order of venomous colubrine snakes, or _Ophidia colubriformes Venenosi_, those which outwardly have the aspect of harmless snakes, while yet furnished with poison fangs. In the chapter on Dentition, these distinctions, facilitated by the illustrations, are more fully explained; here it need only be said that though they have smaller jaws and shorter fangs than many other venomous snakes of their size, the virus is plentiful, and so active that the danger from the bite is great. All the pelagic serpents have also a few simple teeth behind the fangs; therefore, as Fayrer warns the natives, it does not do to trust to the _appearance_ of the wound, which, though looking like the bite of a harmless snake, would demand immediate remedies. A certain conviction of danger is that the bite being inflicted in salt water, would leave no doubt as to the nature of the snake. Even a painless wound it is not safe to trust; and Sir Joseph Fayrer gives several such warnings among his cases of bite from sea snakes, two of which I will quote.