462 THE ASCENT OF MAN. 



pieces, the occipital aud temporal each into four, the sphenoid into 

 eight, repeating what we find as we descend the vertebrate scale. 



Many of these peculiarities may remain throughout life. Such are 

 the inter-parietal bone (found very frequently in ancient Peruvian and 

 Arizonian skulls), the division of the frontal aud temporal bones each 

 into two, the persistence of the intermaxillary boues aud of that divi- 

 sion of the cheek or malur bone known as the os japonicum. Even cleft 

 palate, a deformity and defect in man, merely re-produces a state nat- 

 ural to some of the lower mammals. 



There are also present structures that are homologous with the so- 

 called visceral arches represented in the thorax by ribs. Such are the 

 lower jaw, the hyoid bone, and the thyroid cartilage. A study of the 

 embryo shows us that these are portions of a series of bars primitively 

 arranged on the plan of the branchial apparatus of the water-breath- 

 ing vertebrates. Each bar has its appropriate skeleton aud vascular 

 supply and is separated from the contiguous ones by a cleft that at 

 first passes entirely through the soft tissues and communicates with the 

 primitive visceral cavity. These clefts may persist and cause serious 

 deformities. The skeleton of the mandibular and hyoid bars is remark- 

 able as containing indications of elements present in the lower verte- 

 brates. In fishes, the lower jaw articulates with a large bone appar- 

 ently not found in mammals, but on tracing carefully the development 

 of the mammalian skuUit is found that this bone is represented by the 

 incus, one of the minute ossicles of the ear. In the fcetus the primi- 

 tive lower jaw, in the shape of a bar of cartilage, actually extends into 

 the ear cavity and the upper end of it remains as the malleus. Relics 

 of the hyoid or second branchial arch are also found, — the styloid proc- 

 ess of tbe temporal bone being one of them. 



The capacity of tlie cranium is usually held to distinguish man 

 remarkably, yet the lowest microcephali approach the apes in this res- 

 pect and the lower races have unquestionably smaller brains than the 

 higher. As far as can be judged, there has also been an increase lii 

 average capacity during historic times. One fact ijointed out by Gra- 

 tiolet is very significant. In monkeys and in the inferior races the ossi- 

 fication of the sutures commences at the anterior part of the head, while 

 in Europeans these sutures are the last to close. This would indicate 

 a greater and longer continued increase of the frontal lobes of the brain. 



Tbe same remarks may be made concerning the facial angle and 

 l^roguatliism. While by none of the different angles proposed have we 

 been able to definitely separate distinct races, yet we find that the 

 angle of the lower races and of microcephali approaches that of the 

 anthropoid apes, and that as the capacity of the skull has increased the 

 jaw has been thrust back under it to support the weight. This shorten- 

 ing of the jaw gives the characteristic expression of the civilized face. 

 We at once recognize a brutal physiognomy by the projection and de- 

 velopment of the great masticating apparatus, used in most animals 



