Dwight has an excellent chapter on anatomical variations and anomalies. (_Cf._ “Thoughts of a Catholic Anatomist,” 1911, ch. IX.) He tells us that “a thigh bone a little more bent, an ear a little more pointed, a nose a little more projecting ... a little more or a little less of anything you please—this is variation.” “An anatomical anomaly,” he says, “is some peculiarity of any part of the body which cannot be expressed in terms of more or less, but is distinctly new.” He divides the latter into two classes, namely: those which consist in the repetition of one or more elements in a series, _e.g._ the occurrence of supernumerary legs in an insect, and those which consist in the suppression of one or more elements in a series, _e.g._ the occurrence of eleven pairs of ribs in a man. Variations and anomalies are fluctuational or mutational, according as they are based on changes in the soma alone, or on changes in the germ plasm. Variations, however, are more likely to be non-inheritable fluctuations, and anomalies to be inheritable mutations. We shall speak of the latter presently. In the meantime we may note that the main trouble with interpreting these anatomical irregularities as “reversive” or “atavistic” is that they would connect man with all sorts of quite impossible lines of descent. “In my early days of anatomy,” says Dwight, “I thought that I must be very ignorant, because I could not understand how the occasional appearance in man of a peculiarity of some animal outside of any conceivable line of descent could be called a reversion, as it soon became the custom to call it.... It was only later that I grasped the fact that the reason I could not understand these things was that there was nothing to understand. It was sham science from beginning to end.” (_Op. cit._, p. 209.) By way of anomaly, almost any human peculiarity can occur in animals, and, conversely, any bestial peculiarity in man, but the resemblance to man of an animal outside of the alleged line of human descent represents a grave difficulty for the theory of evolution, and not an argument in its favor.