A Transitional Form between Man and the Apes. 15 
maurus equal to 90°; in Macacus cynomolgus to 84°. In the cranium of Pithee- 
anthropus, however, it is equal to 115°, which is much nearer to Man; for in recent 
human skulls it is generally about 130°; in the microcephal Joe, described by 
Professor Cunningham, 112°; in the skull No. 2 of Spy, 124°. 
Certainly the position of the superior nuchal line is somewhat variable in every 
species, this point shifting up and down according to the development of the 
nuchal muscles; but then the inclination of the nuchal plane to the glabellar- 
opisthion line may still be nearly constant in each species, as it seems to me to 
be according to the human and Ape skulls I have just mentioned, nor could the 
degree of this inclination in Pithecanthropus be much influenced by the varying 
position of the superior nuchal line. 
It might be possible that among an immense number of Anthropoid crania one 
is to be found which more approached the human proportions than the six crania 
of Anthropoid Apes stated, belonging to four genera and six species. This cranium 
of Pithecanthropus might also be an exceptional case in its kind and very different 
from the average. But, on the one hand, among a large number of Anthropoid 
crania, and a still greater number of human skulls, I did not find, even in a single 
case, a considerable deviation from the average ; on the other hand, the probability 
that the fossil cranium found should be an exceptional case is very small. 
As Professor Rosenberg, of Utrecht, in the discussion upon these fossils, which 
took place during the Leiden Zoological Congress, rightly remarked, the American 
Monkeys are even nearer to Man by the strong forward slope of the nuchal part of 
the occiput, than the Anthropoid Apes, and they do not walk more upright. As it 
appears to me the New World Apes, however, stand too far off from Man to allow 
of a more direct comparison, and to regard this feature as a real homologue of that 
in Man. For the same reason nobody would be likely to bring the analogous high- 
arched forehead of those Apes in closer comparison with the human frontal arch. 
Almost the same divergence relative to the skull exists in the interpretation of 
the molar tooth which I described. W. Krause* said of it that there is no doubt 
that it is the molar tooth of an Ape. Ten Katef had the same opinion. Rudolph 
Martin,{ on the contrary, said it is totally human-like, and only different from the 
human tooth by a greater breadth of the crown. The reviewer in “‘ Nature”§ also 
thinks the tooth may be human. According to Arthur Keith,|| however, it closely 
resembles the very variable third molar of the Orang. He thinks the crenation of 
the posterior fringe of the tooth is practically diagnostic of its being an Orang’s 
tooth. On a later occasion, however, Keith regards the tooth as human. 
Professor Cunningham** said that the fossil tooth is fashioned more after the 
* 1. ¢. } “Nederlandsch Koloniaal Centraalblad, Leiden, 1895,” p. 128. t “Globus,” Z. ¢. 
§ “‘ Nature,” 7. ¢. || ‘‘ Proceed. Anat. Soc.,” J. ¢. 
q ‘‘ Science Progress,” July, 1895, vol. iii., p. 850. 
**% ‘6 Nature,” 7. ¢. 
