Crossword-Solution: SULCUS 6 letters, 2 clues 🏆 scrabble score: 8

Every principal gyrus and sulcus of a chimpanzee’s brain is clearly represented in that of a man, so that the terminology which applies to the one answers for the other.

For, in the chimpanzee, the more or less extensive obliteration of the external perpendicular sulcus by “bridging convolutions,” on one side or the other, has been noted over and over again by Prof.

Even were the presence of the temporo-occipital, or external perpendicular, sulcus, a mark of distinction between the higher apes and man, the value of such a distinctive character would be rendered very doubtful by the structure of the brain in the Platyrrhine apes.

The first which appears, in fact, lies on the inner face of the hemisphere (whence doubtless Gratiolet, who does not seem to have examined that face in his foetus, overlooked it), and is either the internal perpendicular (occipito-parietal), or the calcarine sulcus, these two being close together and eventually running into one another.

Now this fact, taken together with the circumstance that the antero-temporal sulcus is present in such Platyrrhini as the Saimiri, which present mere traces of sulci on the anterior half of the exterior of the cerebral hemispheres, or none at all, undoubtedly, so far as it goes, affords fair evidence in favour of Gratiolet’s hypothesis, that the posterior sulci appear before the anterior, in the brains of the Platyrrhini.