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Mr. Victor Horsley—Cranio-Cerebral Topography.

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part of the gyrus fornicatus vel calloso-marginalis, constituting the anterior
two-thirds of the limbic lobe.

Similarly it will be remembered that the determination of the posterior
extremity of the calloso-marginal sulcus gives the anterior limit of the
quadrate lobule, the posterior border of which is found by fixing the parietooccipital
fissure.

(C) Occipital Lobe.—>The gyri of the occipital lobe are all contained
within such a limited area, viz. little more than the area of the
superior occipital fossae, as to make their topographical exposure a matter
of no difficulty. Moreover, at the present moment the arrangement and
homologies of so many of the sulci are still questions sub judice that no
stress can profitably be laid upon the situation of such furrows as are
commonly described, except the most evident.

Sulcus Transversus Occipitalis.—Of these the first is termed the sulcus
transversus occipitalis, and by some the sulcus occipitalis superior. This I
think Prof. Cunningham has certainly shown to be simply the bifurcated
extremity of the intraparietal sulcus (ramus sagittalis). It corresponds
commonly with the junction of the superior and middle third of the distance
between the lambdoid suture and the superior curved line, the highest
point of which marks the lower margin of the occipital lobe. The furrow
which is frequently termed the inferior sulcus divides horizontally the
remnant of the outer surface of the lobe, and bears the same relation to
the border of the hemisphere as the middle temporal sulcus does further
forwards.

Fissura Calcarina.—The great importance of the calcarine fissure in
relation to the representation of central vision is obvious from so many
considerations as to make the exact determination of the fissure very
necessary. The fissure terminates posteriorly by a bifurcation which,
according to Professor Cunningham, is more correctly the middle portion
of a " posterior calcarine sulcus." This bifurcation has a vertical direction,
and lies usually upon, sometimes, just inside the margin of the hemisphere.
The point to be fixed is the junction between it and the horizontal portion
of the rest of the fissure. In the first place this point is always well above
and in front of the occipital pole. At present it is only possible to estimate