The purpose of this article is to give a general indication of the present state of our knowledge of whales, regarded as an element of the oceanic fauna, and to indicate some of the more important problems which still await solution. The term “whales” is used here to include only the largest of the Cetacea, which are the Right whales, the Rorquals and the Sperm whale; and the subject has to do with these whales in the collective sense, that is to say their habits as a community, and their breeding, growth and distribution, especially in the southern hemisphere, rather than with such matters as comparative anatomy and physiology.