HEIDELBERG MAN 
243 
berg mandible shows more primitive characters ; its 
upper or alveolar border is more projecting ; there is no 
indication of a chin. In the Spy specimen the rudiment 
of a chin is apparent. Again, on the posterior aspect of 
the symphysis the genial pit — a simian structure — is 
almost filled up in the Spy specimen. This pit is 
open almost to the extent seen in young gorillas in the 
Heidelberg mandible (see also page 433). 
There is another feature worthy of note, illustrated by the 
various drawings represented in fig. 82. In these drawings 
»E/DELBERG 
6Py 
Fig. 
60 <K) 20 20 ib 
86. — Outline of the Heidelberg mandible compared with the Spy mandible. 
the Heidelberg, the Spy, a Tasmanian mandible, and a 
European mandible are represented from exactly the 
same point of view — at right angles to the chewing plane 
of the teeth. Such a view gives a clear idea of what is 
meant by the opening out of the floor of the mouth. 
The lower border of the mandible bounds that floor. 
Even in the primitive Tasmanian very little of the 
symphysis or of the lower border of the mandible is seen 
within the arcade of the teeth (fig. 82). In the 
Heidelberg mandible, and to some degree in that from 
Spy, the lower part of the symphysis encroaches, as in 
the ape (see fig. 165, p. 446), on the floor of the mouth. 
