350 
THE ANTIQUITY OF MAN 
the skull, man and ape are very much alike. In the ape 
the basilar process, and especially the petrous bones, are 
large. The petrous bones, which contain the organ 
of hearing, are of great size in the anthropoid ape, 
because they have also to afford a joint for massive 
jaws and attachment for the huge muscles of the neck. 
Two important points should be noted in the human 
skull. The brain has so increased in mass that the 
petrous pyramids of the temporal bones have been 
forced into a horizontal position. The opening of the 
TEMPORAL 
AtiTICULAR 
Fig. I20. — A. Transverse vertical section of the skull of an Australian aboriginal, 
to show the bones forming the base, side, and roof of the brain cavity. B. Of 
an orang, to show the bones forming the base, sides, and roof of the brain 
cavity. 
ear-passage lies below the level of the brain in the human 
skull. In the anthropoid the petrous bone is set 
obliquely ; the ear-hole is situated at a higher level as 
regards the brain cavity. The other point which is 
important for our present purpose is that the petrous 
bone reaches within a definite distance of the middle 
line of the base of the skull ; it affords us a means of 
estimating the width of a skull. Now we have the left 
temporal bone of the Piltdown skull — almost the whole 
of the petrous portion and a great part of the side plate 
or squama. 
In fig. 121 the composition of the Piltdown skull in 
