“Former attempts to analyze the relations between body weight and brain weight suffer from three deficits: (1) they presuppose a correlation between intelligence and brain weight, (2) they make suppositions about the intelligence of animals which are unproven, and (3) they are based on a conception of cortical function which can no longer be considered valid.... There is a close correlation between the logarithms of brain and body weight, and this co-relation is linear. Brain weight increases as the 0.655th power of body weight. The value of the cephalization co-efficient k differs from species to species. _Whether or not this is an indication of the intelligence of animals must be left to the psychologists to answer._” One of the problems that the whales have, as compared to, say, the large shark, is breathing air while living in the sea. This requires that these animals reach the air-water interface relatively frequently—at least every one hour and a half for the bottlenose whale (_Hyperoödon_), three-quarters of an hour for the Sperm Whale (_Physeter catadon_), and every six minutes for _Tursiops truncatus_. This puts very stringent requirements on the relationship of the whales to other events within the sea. Each whale must know where the surface of the sea is at each instant and compute his future actions so that when he does run out of air he is near the surface. He is essentially a surface-to-depth and depth-to-surface oriented animal. He must travel at high speed at times in order to recapture enough air to continue whatever he is doing under the surface. This means that he must calculate his chances of obtaining a good breath of air during rain storms and similar situations. He can be violently thrown around at the surface unless he comes up in the trough rather than at the crest of the wave. Such calculations probably require an exercise of something more than just “instinct.” Water-breathing animals, on the other hand, have no need for such calculations. If the surface gets rough, they move downward and stay there. The required maneuvers are very much simpler and the amount of computation is very much less. This requirement for the whales implies that the information coming from every one of the senses, not just the skin, needs to be correlated very rapidly and in complex patterning to allow the animals to predict their future course safely and accurately. It also requires the use of large amounts of information from memory. The predators of the sea, other than the whales themselves, make life in the sea rather a complex business for mammals. The very large sharks can and do attack whales, dolphins, and porpoises. At times such attacks are by overwhelming numbers of sharks on a relatively small number of dolphins. All of the older animals in our experience have at least one shark bite on them—the younger animals are protected by the older ones and most of them are not so dramatically scarred.