80 



is thicker and stronger than in the chimpanzee. In both, however, 

 it is a true thumb, by position, diverging from the other toes, in the 

 gorilla, at an angle of 60 from the axis of the foot. 



Man has 12 pairs of ribs, the gorilla and chimpanzee have 13 

 pairs, the orangs have 12 pairs, the gibbons have 13 pairs. Were 

 the naturalist to trust to this single character, as some have trusted 

 to the cranio -facial one, and in equal ignorance of the real condition 

 and value of both, he might think that the orangs (Pithecus) were 

 nearer akin to man than the chimpanzees (Troglodytes) are. But 

 man has sometimes a thirteenth pair of ribs ; and what we term 

 * ribs' are but vertebral elements or appendages common to nearly 

 all the true vertebrae in man, and only so called, when they become 

 long and free. The genera Homo, Troglodytes, and Pithecus, have 

 precisely the same number of vertebrae : if Troglodytes, by the 

 development and mobility of the pleurapophyses of the 20th ver- 

 tebrae from the occiput seem to have an additional thoracic vertebra, 

 it has one vertebra less in the lumbar region. So, if there be, as 

 has been observed in the same genus, a difference in the number of 

 sacral vertebrae, it is merely due to a last lumbar having coalesced 

 with what we reckon the first sacral vertebra in man. 



The thirteen pairs of ribs, therefore, in the gorilla and chim- 

 panzee are of no weight, as against the really important characters 

 significative of affinity with the human type. But, supposing the 

 fact of any real value, how do the advocates of the superior resem- 

 blance of the gibbon's skeleton to that of man dispose of the 

 thirteenth pair of ribs ? 



In applying the characters of the skull to the determination of 

 the important question at issue those had first to be ascertained by 

 which the genus Homo trenchantly differs from the genus Simla, of 

 Linnaeus. To determine these osteal distinctions I have compared 

 the skulls of many individuals of different varieties of the human 

 race together with those of the male, female, and young of species 

 of Troglodytes, Pithecus, and Hylobates; the detailed results of 

 which comparisons will be found in the Catalogue of the Osteo- 

 logical Series in the Museum of the Royal College of Surgeons, 

 4to, 1853. In the present Appendix, I restrict myself to a few of 

 these results. 



The first and most obvious differential character is the glo- 

 bular form of the brain-case, and its superior relative size to the 

 face, especially the jaws, in man. But this, for the reasons al- 

 ready assigned, is not an instructive or decisive character, when 



