“Cutaneous respiration is not unique in Typhlogobius and the Amblyopsidæ. In the viviparous fishes of California the general surface, and especially the fins, which have become enormously enlarged, serve as respiratory organs during the middle and later periods of gestation; the fins are a mass of blood-vessels, with merely sufficient cellular substance to knit them together. There is, however, no pink coloration.” [Illustration: FIG. 15.--_Mancalias Schufeldtii_, 372 fathoms.] Skin respiration would account for the extreme resistance to asphyxiation in Amblyopsis and Typhlogobius. About forty-five examples of Amblyopsis were carried in a pail of water four hundred miles by rail, with only a partial change of water three times during twenty-four hours. A smaller number may be kept for days or weeks--probably indefinitely--in a pail of water without change. The characteristics of Typhlogobius along this line have been set forth elsewhere. Sticks, straws, etc., are never avoided by the fishes even when perfectly imperturbed. By this I mean that they are never seen to avoid such an object when it is in their path. They swim against it and then turn. An object falling through the water does not disturb them, even if it falls on them. A pencil gently moved about in front of them does not disturb the fishes much, but if the pencil is held firmly in the hand it is always perceived, and the fish comes to a dead halt ten or fifteen millimetres before it reaches such an object. On the other hand, they may be touched on the back or tail before they start away. They glide by each other leisurely and dignified, and if they collide, as they sometimes do, they usually show no more emotion than when they run against a stick. But this indifference is not always displayed, as we shall see under the head of breeding habits. A number kept in an aquarium with a median partition, in which there was a small opening, were readily able to perceive the opening, swimming directly for it when opposite it. This observation is in direct contrast to their inability to perceive solid substances in their path. A sharp tap on the sides of an aquarium in which six blind fishes were swimming, where they had been for a number of days undisturbed, in a dark room, caused nearly all of them to dart rapidly forward. A second tap produced a less unanimous reaction. This repeated on successive days always brought responses from some of the inmates of the aquarium. Those responding were not necessarily the nearest to the center of disturbance, but sometimes at the opposite side of the aquarium or variously distributed through it. After a few days the fishes took no notice of the tapping by any action observable in the artificially lighted room.