TRANSACTIONS OF SECTION H. 893 



usually between the second and sixth years of age. It has been noticed by 

 anthropologists that luetopism, as the anomalous non-union of the halves of this 

 bone has been termed, is rare among microcephalic races, occurring only in about 

 1 per cent, among Australian skulls. Increased growth of the frontal lobes 

 as the physical accompaniment of increased intellectual activity interposes an 

 obstacle to the easy closure of this median suture, and so in such races as the 

 .ancient Egyptian, with a broader forehead, metopism becomes commoner, rising 

 to 7 per cent. In modern civilised races the percentage ranges from 5 to 10. 

 In following out the details of this enumeration, I have spoken as if the micro- 

 dontal condition had been the primary one, whereas all the available evi- 

 dence leads to show that the contrary was the case. The characters of all the 

 early crania, Neanderthal, Engis, and Oromagnon, are those of macrodonts. The 

 progress has been from the macrodont to the microdont, as it probably was from the 

 microcephalic to the macrocephalic. 



The effects of the variations in size of the teeth are numerous and far-reaching. 

 The fluctuation in the weight of the jaw depending on these variations has an 

 important influence on the centre of gravity of the head, and affects the set of the 

 skull on the vertebral column. This leads to a consequent change in the axes of 

 the occipital condyles, and it is one of the factors which determines the size of the 

 neck-muscles, and therefore the degree of prominence of the nuchal crests and 

 mastoid process. 



As the teeth and alveolar arches constitute a part of the apparatus for 

 articulate speech, so these varieties in dental development are not without con- 

 siderable influence on the nature of the sound produced. The necessarily larger 

 alveolar arch of the macrodont is hypseloid or elliptical, more especially when 

 it has to be supported on a narrow frontal region, and this is associated with a 

 more extensive and flatter palatine surface. This, in turn, alters the shape of 

 the mouth cavity and is associated with a wide fiat tongue, whose shape par- 

 ticipates in the change of form of the cavity of which it is the floor. The mus- 

 culature of the tongue varies with its shape, and its motions, upon which articular 

 speech depends, become correspondingly modified. For example, the production 

 of the sharp sibilant ' s ' requires the approximation of the raised flexible edge 

 of the tongue to the inner margins of the teeth behind the canines, and to the 

 palatine margin close behind the roots of the canine and lateral incisor teeth. 

 This closes the vocal tube laterally, and leaves a small lacuna about 5 mm. wide 

 anteriorly, through which the vibrating current of air is forced. A narrow strip 

 of the palate behind the medial halves of the median incisors bounds this lacuna 

 above, and the slightly concave raised tongue-tip limits it below. • 



AVith the macrodont alveolar arch, and the correspondingly modified tongue, 

 sibilation is a difficult feat to accomplish, and hence the sibilant sounds are 

 practically unknown in all the Australian dialects. 



It is worthy of note that the five sets of muscular fibres, whose function it is to 

 close laterally the flask-like air-space between the tongue and the palate, are much 

 ■less distinct and smaller in the tongues of the Australians which I have examined 

 .than in the tongues of ordinary Europeans. 



There is a wide field open to the anatomical anthropologist in this investigation 

 of the physical basis of dialect. It is one which requires minute and careful work, 

 but it will repay any student who can obtain the material, and who takes time 

 and opportunity to follow it out. The anatomical side of phonology is yet an 

 imperfectly known subject, if one may judge by the crudeness of the descriptions 

 of the mechanism of the several sounds to be found even in the most recent text- 

 books. As a preliminary step in this direction we are in urgent need of an appro- 

 priate nomenclature and an accurate description of the muscular fibres of the 

 tongue. The importance of such a work can be estimated when we remember that 

 there is not one of the 260 possible consonantal sounds known to the phonologist 

 which is not capable of expression in terms of lingual, labial, and palatine muscu- 

 lature. 



The acquisition of articulate speech became possible to man only when his 

 alveolar arch and palatine area became shortened and widened, and when his 



