RELATIONS OF SPEECH TO HUMAN PROGRESS 533 



human race, is nothing like complete enough for an inquiry of 

 this kind ; but it should be easy, considering the vast amount of 

 material now available in our museums, for any one who has the 

 time at his disposal to make a fairly complete comparative collec- 

 tion of such plaster casts. The process is very simple. The 

 writer's practice has been to carry about him some pieces of 

 wax, preferably the paraffin wax of which ordinary candles are 

 made, which can be softened at a comparatively low temperature. 

 A piece no bigger than a walnut suffices for the purpose of 

 taking an impression of the part of the lower jaw involved. The 

 whole proceeding takes but a few moments, and a permanent 

 record is obtained which can be stored away and easily trans- 

 formed into a plaster cast at any convenient time. 



Incomplete as my material is it already demonstrates some 

 interesting facts bearing upon the relations of articulate speech 

 to human progress. There can be little doubt that the almost 

 universal absence of the tubercles in the Bushman, and their 

 exceedingly imperfect development among other primitive races 

 which we know to speak languages which, from our European 

 point of view, are very imperfect, tend to show that those pre- 

 historic peoples which present a like peculiarity must have been 

 far behind modern men in this respect. 



There is a peculiarity about the Heidelberg and certain other 

 prehistoric jaws which I have examined which it may be as well 

 to draw[attention to here, as it has already given rise to misunder- 

 standings as to the value of the evidence from the genial tubercles. 

 Beneath the prominence for the attachment for the genio-glossus 

 muscle, and nearer the lower rim of the bone, are two smaller 

 prominences which often take the form of slight rough ridges 

 more or less united. These are found not only in man but in 

 the apes and certain of the lower animals. They are the points 

 of attachment for a muscular strip which has nothing to do with 

 the tongue, called the genio-hyoideus, because it connects the chin 

 with the hyoid bone. In the Heidelberg jaw there is a pro- 

 minence representing this tubercle, but if the part above it is 

 examined carefully the region occupied in our jaws by the 

 prominent genial tubercles is represented by a decided depres- 

 sion. Most jaws of the Neanderthal or Spy type seem to 

 indicate a state of development comparable to the Bushmen and 

 Hottentots. The Piltdown jaw unfortunately is broken off at 

 some distance from the symphisis, and hence this most interest- 



