the two sub-orders have been developing quite independently of each other in the western and eastern hemispheres. That is a most important point in view of the genealogy of our race; for man bears all the marks of a _true catarrhina_; he has descended from some extinct member of this sub-order in the Old World. The numerous types of _catarrhinae_ which still survive in Asia and Africa have been formed into two sections for some time--the tailed, doglike apes (the _cynopitheci_) and the tailless, manlike apes (the _anthropomorpha_). The latter are much nearer to man than the former, not only in the absence of a tail and in the general build of the body (especially of the head), but also on account of certain features which are unimportant in themselves but very significant in their constancy. The sacrum of the anthropoid ape, like that of man, is made up of the fusion of five vertebræ; that of the _cynopithecus_ consists of three (more rarely four) sacral vertebræ. The premolar teeth of the _cynopitheci_ are greater in length than breadth; those of the _anthropomorpha_ are broader than they are long; and the first molar has four protuberances in the former, five in the latter. Furthermore, the outer incisor of the lower jaw is broader than the inner one in the manlike apes and man; in the doglike ape it is the smaller. Finally, there is a special significance in the fact, established by Selenka in 1890, that the anthropoid apes share with man the peculiar structure of the discoid _placenta_, the _decidua reflexa_, and the pedicle of the allantois. In fact, even a superficial comparison of the bodily structure of the _anthropomorpha_ which still survive makes it clear that both the Asiatic (the orang-outang and the gibbous ape) and the African (the gorilla and chimpanzee) representatives of this group are nearer to man in build than any of the _cynopitheci_. Under the latter group we include the dog-faced papiomorpha, the baboon, and the long-tailed monkey, at a very low stage. The anatomical difference between these low papiomorpha and the most highly developed anthropoid apes is greater in every respect, whatever organ we take for comparison, than the difference between the latter and man. This instructive fact was established with great penetration by the anatomist Robert Hartmann, in his work on _The Anthropoid Apes_;[10] he proposed to divide the order of _Simiae_ in a new way--namely, into the two great groups of _primaria_ (man and the anthropoid ape) and the _simiae_ proper, or _pitheci_ (the rest of the catarrhinæ and all the platyrrhinæ). In any case, we have a clear proof of _the close affinity of man and the anthropoid ape_.