The interesting discoveries of Roncoroni, regarding the peculiarities of certain cells of the cerebral cortex in criminals, though widely discredited at first, have been subsequently confirmed by Pelizzi. In this case also it appears that we have to do with atavism (Pelizzi, “Idiozia ed Epilessia,” _Arch. di psichiatria_, 1900, p. 409). Not only in the skulls and brains of criminals, but also in almost all their other organs, we find abnormalities with greater average frequency than among the general population, and this is especially true of rudimentary organs, those which constitute the majority of the so-called secondary and tertiary sexual characters. Many of these abnormalities may be regarded as primatoid or atavistic; others appear to be mainly dependent upon disturbance or arrest of development. All alike, in so far as they are not merely characters acquired during the lifetime of the individual, give the impression that the criminal is a being whose humanity is not completely developed. This does not exclude the fact that the criminal himself, in the light of his own peculiar valuation of social and legal value, is apt to be firmly convinced that his is a superman. This arrest at an earlier stage of development gives rise, in respect of numerous traits, to an approximation in the “criminal type” to the characteristics of one or other of the extant savage races of mankind—races such as the Australian, etc., which, owing to prolonged isolation from other types and, possibly, also to less rigorous selection and therefore less marked differentiation, in consequence of a less severe struggle for existence, have been able for thousands of years to retain their primitive characteristics. We are, however, compelled to assume that many savage races have been unable to raise themselves above their present low level of intellectual, economic, and social culture, not merely on account of the slighter operation of the factors of differentiation, but also on account of an inferior innate developmental capacity. In philosophical terminology we should perhaps therefore say that the world of crime recruits itself from among the number of the less developed individuals of the nation concerned; for it is an obvious deduction from the law of organic variability that among all the individuals born as members of any civilized race there should be some who are congenitally incapacitated to attain the normal mean level of development peculiar to that race. It is not proposed to deal here at any length with the innumerable anthropological characteristics of criminals other than those found in the skull and the brain, but the physiognomically important characters deserve separate notice.