Freiburger historische Bestände - digital

206

Cunningham Memoirs.

Further, the study of these anthropoid hemispheres suggests the proper
interpretation to place upon the occurrence of a ramus postcentralis
superior. It is merely one of a series of transverse secondary furrows
which tend to appear on the ground above the primitive simple and continuous
intraparietal sulcus (superior parietal lobule). These in the evolution

. Fissure of Rolando.

. Sulcus postcentralis inferior.

. Two parts of sulcus postcentralis superior.

. Eamus horizontalis.

. Eamus occipitalis.

. First parieto-occipital annectant gyrus.

. Parieto-occipital fissure.

. Bottom of the " Affenspalte."

. Cut surface of the occipital operculum.

. Fissure of Sylvius.

. Parallel sulcus.

Fig. 37.—Eight hemisphere of a male orang-utan about six years' old. The occipital operculum has
been removed. Drawn by the American apparatus for tracing orthogonal projections of
the skull. The hinder end of the hemisphere was raised considerably, in order that the
parts under cover of the occipital operculum might be brought into view.

of the cerebral surface make their appearance in regular^sequence from
before backwards. The most anterior of the series comes into existence
first, and when once fairly established it tends to join the ramus postcentralis
inferior. It is the ramus postcentralis superior, and it affords an
excellent example of how a furrow of secondary importance in a low form
may assume a primary importance in a higher form. The others are very
rarely seen in the lower apes; one or perhaps two occur in the chimpanzee,
and, as a rule, they remain separate and distinct. In man they are more