1047 
attached to the calvarial bone upon which it glides, but firmly 
bound to the hairy skin of the head, extends over the calvaria 
between the fascia temporalis of the two sides, in which it is lost. The 
backmost belly, formed on either side by the musculus occipitalis, 
starts, in modern Man, in different extension and coherency from the 
occipital bone, above the superior curved line, and laterally to the 
basis of the mastoid process of the temporal bone, hence above the 
muscles that pull the bead backward. The front muscle belly, formed 
by the two musculi frontales, rises from the epicranial aponeurosis, 
and its fibers terminate, in Man of the modern type, besides in the 
skin of the root of the nose and of the brows over their entire 
length, at the median part of the frontal bone and at the outside 
of the orbital arch, but here in very various extension and coher- 
ency; most uniform is still the lateral part of this attachment, namely 
near and at the processus zygomaticus frontalis. More coherent is 
this bony origin (directly or indirectly by fascia) in Apes that possess 
a torus supraorbitalis *). 
This apparatus must have a more important function and especi- 
ally (in the Neandertal Man) have had a more important function 
than elevating the eye-brows and wrinkling the forehead. Its principal 
action apparently is, as was stated above, the distribution of the 
strain, which is exited by the muscles of the neck, by transference 
to the frontal orbital arches, and as stress, to the malar bones and 
elastic zygomatic arches back to the occipital bone.’) 
The functional significance of the torus supraorbitalis in most 
Apes, and its absence in the Orang-utan and Homo sapiens thus | 
becomes clear; besides, its formation can also be explained directly 
mechanically by the application of Arcuer’s demonstration. 
The validity of this view may also appear from what is found 
in American Apes (Chrysothrix, Cebus, Ateles). Here the planum 
nuchale, to which the muscles that draw the head back, are attached, 
makes much smaller angles with the transversal glabella-inion plane, 
hence no very great strain can arise in the cranial vault, and there 
was not developed a torus supraorbitalis. 
1) In an analogous way as the apparatus of the musculus epicranius protects 
the calvaria from the violence of the cervical muscles, the strong fascia temporalis, 
stretched out between the temporal crest and superior temporal line, and the 
zygomatic arch, and serving for partial attachment of the musculus temporalis, 
protects it against the violence of the latter muscle, and the zygomatic arch against 
that of the musculus masseter. This apparatus, though exceedingly strong in the 
Apes, does probably not contribute to the formation of the lateral part of the 
torus supraorbitalis, but only of the temporal crest. 
3) Cf. on those muscles in Apes and Man: G. Ruce, Untersuchungen über die 
Gesichtsmuskulatur der Primaten, p. 37—51 and 84—983. Leipzig 1887. 
68* 
