It is certainly significant to find one of the earliest instances of genuine parental affection exhibited by the male. This reversal of the usual role of the sexes is common among fishes, among whom care of offspring is very little developed. In some species the eggs are carried about by the father--the male sea-horse, for instance, has a pouch developed for this purpose; in other cases the male incubates, or cares for the ova. Sometimes, however, it is the female who performs this duty, but the known cases are few.[47] Some exceedingly curious examples of male parental care occur among the amphibians. One of the most interesting is that of the obstetric frog, where the male helps to remove the eggs from the female, then twists them in the coils around its hind legs and buries himself in the water, until the incubation period is over and the tadpoles escape and relieve him of his burden. In other species the croaking sacs of the males, which were previously used for amatory callings, become enlarged to form cradles for the young. There are also instances of the female co-operating with the male in this care of offspring. Thus in the Surinam toad the male spreads the ova on the back of the female, where skin cavities form in which the tadpoles develop. In other cases the eggs are carried in the dorsal pouches of the females. It would almost seem that in this early time Nature was making experiments as to which parent was the better fitted to rear and protect the young! But let us return to our present examination of animal love-making. In many diverse forms there is a very remarkable courtship of touch, often prolonged and with beautiful refinements, before the climax is reached, when the two bodies unite. Racovitza[48] has beautifully described the courtship of the octopus, which is carried out with considerable delicacy, and not brutally as before had been believed. "The male gently stretches out his third arm on the right and caresses the female with its extremity, eventually passing it into the chamber formed by the mantle. The female contracts spasmodically, but does not attempt to move. They remain thus about an hour or more, and during this time the male shifts his arm from one viaduct to the other. Finally, he withdraws his arm, caresses her with it for a few moments, and then replaces it with his other arm."