cal condition； are by far the most serviceable for classification。〃 （Loc。 cit。） It has also to be remembered that NUMEROUS separate points of agreement are of much greater importance than the amount of similarity or dissimilarity in a few points。
The hypotheses as to descent current at the present day may be divided into two main groups。 The first group seeks for the roots of the human race not among any of the families of the apesthe anatomically nearest formsnor among their very similar but less specialised ancestral forms； the fossil representatives of which we can know only in part； but； setting the monkeys on one side； it seeks for them lower down among the fossil Eocene Pseudo… lemuridae or Lemuridae （Cope）； or even among the primitive pentadactylous Eocene forms； which may either have led directly to the evolution of man （Adloff）； or have given rise to an ancestral form common to apes and men （Klaatsch （Klaatsch in his last publications speaks in the main only of an ancestral form common to men and anthropoid apes。）； Giuffrida…Ruggeri）。 The common ancestral form； from which man and apes are thus supposed to have arisen independently； may explain the numerous resemblances which actually exist between them。 That is to say； all the characters upon which the great structural resemblance between apes and man depends must have been present in their common ancestor。 Let us take an example of such a common character。 The bony external ear…passage is in general as highly developed in the lower Eastern monkeys and the anthropoid apes as in man。 This character must； therefore； have already been present in the common primitive form。 In that case it is not easy to understand why the Western monkeys have not also inherited the character； instead of possessing only a tympanic ring。 But it becomes more intelligible if we assume that forms with a primitive tympanic ring were the original type； and that from these were evolved； on the one hand； the existing New World monkeys with persistent tympanic ring； and on the other an ancestral form common to the lower Old World monkeys； the anthropoid apes and man。 For man shares with these the character in question； and it is also one of the 〃unimportant〃 characters required by Darwin。 Thus we have two divergent lines arising from the ancestral form； the Western monkeys （Platyrrhine） on the one hand； and an ancestral form common to the lower Eastern monkeys； the anthropoid apes； and man； on the other。 But considerations similar to those which showed it to be impossible that man should have developed from an ancestor common to him and the monkeys； yet outside of and parallel with these； may be urged also against the likelihood of a parallel evolution of the lower Eastern monkeys； the anthropoid apes； and man。 The anthropoid apes have in common with man many characters which are not present in the lower Old World monkeys。 These characters must therefore have been present in the ancestral form common to the three groups。 But here； again； it is difficult to understand why the lower Eastern monkeys should not also have inherited these characters。 As this is not the case； there remains no alternative but to assume divergent evolution from an indifferent form。 The lower Eastern monkeys are carrying on the evolution in one directionI might almost say towards a blind alleywhile anthropoids and men have struck out a progressive path； at first in common； which explains the many points of resemblance between them； without regarding man as derived directly from the anthropoids。 Their many striking points of agreement indicate a common descent； and cannot be explained as phenomena of convergence。
I believe I have shown in the above sketch that a theory which derives man directly from lower forms without regarding apes as transition…types leads ad absurdum。 The close structural relationship between man and monkeys can only be understood if both are brought into the same line of evolution。 To trace man's line of descent directly back to the old Eocene mammals； alongside of； but with no relation to these very similar forms； is to abandon the method of exact comparison； which； as Darwin rightly recognised； alone justifies us in drawing up genealogical trees on the basis of resemblances and differences。 The farther down we go the more does the ground slip from beneath our feet。 Even the Lemuridae show very numerous divergent conditions； much more so the Eocene mammals （Creodonta； Condylarthra）； the chief resemblance of which to man consists in the possession of pentadactylous hands and feet！ Thus the farther course of the line of descent disappears in the darkness of the ancestry of the mammals。 With just as much reason we might pass by the Vertebrates altogether； and go back to the lower Invertebrates； but in that case it would be much easier to say that man has arisen independently； and has evolved； without relation to any animals； from the lowest primitive form to his present isolated and dominant position。 But this would be to deny all value to classification； which must after all be the ultimate basis of a genealogical tree。 We can； as Darwin rightly observed； only infer the line of descent from the degree of resemblance between single forms。 If we regard man as directly derived from primitive forms very far back； we have no way of explaining the many points of agreement between him and the monkeys in general； and the anthropoid apes in particular。 These must remain an inexplicable marvel。
I have thus； I trust； shown that the first class of special theories of descent； which assumes that man has developed； parallel with the monkeys； but without relation to them； from very low primitive forms cannot be upheld； because it fails to take into account the close structural affinity of man and monkeys。 I cannot but regard this hypothesis as lamentably retrograde； for it makes impossible any application of the facts that have been discovered in the course of the anatomical and embryological study of man and monkeys； and indeed prejudges investigations of that class as pointless。 The whole method is perverted； an unjustifiable theory of descent is first formulated with the aid of the imagination； and then we are asked to declare that all structural relations between man and monkeys； and between the different groups of the latter； are valueless；the fact being that they are the only true basis on which a genealogical tree can be constructed。
So much for this most modern method of classification； which has probably found adherents because it would deliver us from the relationship to apes which many people so much dislike。 In contrast to it we have the second class of special hypotheses of descent； which keeps strictly to the nearest structural relationships。 This is the only basis that justifies the drawing up of a special hypothesis of descent。 If this fundamental proposition be recognised； it will be admitted that the doctrine of special descent upheld by Haeckel； and set forth in Darwin's 〃Descent of Man〃； is still valid to…day。 In the genealogical tree； man's place is quite close to the anthropoid apes； these again have as their nearest relatives the lower Old World monkeys； and their progenitors must be sought among the less differentiated Platyrrhine monkeys； whose most important characters have been handed on to the present day New World monkeys。 How the different genera are to be arranged within the general scheme indicated depends in the main on the classificatory value attributed to individual characters。 This is particularly true in regard to Pithecanthropus； which I consider as the root of a branch which has sprung from the anthropoid ape root and has led up to man； the latter I have designated the family of the Hominidae。
For the rest； there are； as we have said； various possible ways of constructing the narrower genealogy within the limits of this branch including men and apes； and these methods will probably continue to change with the accumulation of new facts。 Haeckel himself has modified his genealogical tree of the Primates in certain details since the publication of his 〃Generelle Morphologie〃 in 1866； but its general basis remains the same。 （Haeckel's latest genealogical tree is to be found in his most recent work； 〃Unsere Ahnenreihe〃。 Jena； 1908。） All the special genealogical trees drawn up on the lines laid down by Haeckel and Darwin and that of Dubois may be specially mentionedare based； in general； on the close relationship of monkeys and men； although they may vary in detail。 Various hypotheses have been formulated on these lines； with special reference to the evolution of man。 〃Pithecanthropus〃 is regarded by some authorities as the direct ancestor of man； by others as a side… track failure in the attempt at the evolution of man。 The problem of the monophyletic or polyphyletic origin of the human race has also been much discussed。 Sergi （Sergi G。 〃Europa〃； 1908。） inclines towards the assumption of a polyphyletic origin of the three main races of man； the African primitive form of which has given rise also to the gorilla and chimpanzee； the Asiatic to the Orang； the Gibbon； and Pithecanthropus。 Kollmann regards existing human races as derived from small primitive races （pigmies）； and considers that Homo primigenius must have arisen in a secondary and degenerative manner。
But this is not the place； nor have I the space to criticise the various special theories of descent。 One； however； must receive particular notice。 According to Ameghino； the South American monkeys （Pitheculites） from the oldest Tertiary of the Pampas are the forms from which have arisen the existing American monkeys on the one hand； and on the other； the extinct South American Homunculidae； which are also small forms。 From these last； anthropoid apes and man have； he believes； been evolved。 Among the progenitors of man； Ameghino reckons the form discovered by him （Tetraprothomo）； from which a South American primitive man； Homo pampaeus； might be directly evolved； while on the other hand all the lower Old World monkeys may have arisen from older fossil South American forms （Clenialitidae）； the distribution of which may be explained by the bridge formerly existing between South A