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28 DIGASTRICUS.
is united with the Os Occipitis. (e) The extent of this origin is
about an inch that from
: it is fleshy upon its outer part, viz.
the Mastoid Process, and tendinous on the inside from the ridge.
From its origin it passes forwards, downwards, and a little
inwards, much in the direction of the posterior edge of the
Mammillary Process ; and forms a round tendon first in its
center and upper surface. This tendon passes on in the same
direction ; and when got near the Os Hyoides, it commonly
perforates the anterior end of the Stylo-Hyoideus Muscle ; and
from the lower edge of this tendon, some fibres seem to go off,
which degenerate into a kind of Fascia, that binds it to the Os
Hyoides; and some of it goes across the lower part of the
Mylo-Hyoidgeus, and joins its fellow on the opposite side ; bind-
ing the Os Hyoides by a kind of belt. At this part the tendon

middle of the muscle in other Carnivora. It would almost seem as if
the unity of the muscle in the Carnivores was produced by the reunion
of the two fasciculi which are common to Man and the Apes. The
straight line pursued by the simple nr.scle in these animals, as
compared with its deflected course in Man, is evidently conducive to
more powerful and direct action in the abduction of the maxilla.
According to Cuvier, the digastric is absent in the Ant-eaters and
Armadillos, its place being supplied by a long and slender muscle which
takes its origin from the sternum, and is inserted into the inferior
border of the jaw.] (1)
(e) [It is observed by Tyson that in the Chimpanzee the digastric does
not arise from the mastoid process of the temporal, as in Man, but from
the occipital bone. He adds, " Drelincourt describes it (the digastricus)
in Apes thus Tendinem habet intermedium pollice longum, etgracilem,
:
enascitur antem non ab apophyse Styloide, sed ab osse Basilari."
According to Vrolik, however, in the Chimpanzee it is attached to the
tuberosity which represents the mastoid apophysis. In the Gorilla,
Duvernoy traces its attachment to a groove behind the mastoid
apophysis.] (2)
(1) Vide Cuvier, op. cit., p. 91 ; Duvernoy, Archives du Museum
d'Histoire Naturelle, Tome viii., p. 182 ; Vrolik, Recherches d'Anatomie
Comparee sur le Chimpanse, Amsterdam, 1841, pp. 17, 26 ; Article
Quadrumana, Todd's Cyclopsedia of Anatomy ; Straus-Durckheim, op. cit.,
p. 218.
(2) Orang Outang, sive Homo Sylvestris, or the Anatomy of a Pygmie, by
E. Tyson, M.D., F.R.S., p. 86 ; Vrolik ; Duvernoy, op. et loc, cit.