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Cunningham Memoirs.

7. During intra-uterine life the anterior end of the insula maintains a
very nearly fixed position with reference to the anterior end of the cerebrum
, whilst the posterior end moves rapidly towards the occipital pole.
After birth the posterior end of the insula is fixed, whilst the anterior
end, as growth advances, oscillates slightly—at first approaching and then
retreating from the anterior end of the cerebrum.

8. An anterior limb of the Sylvian fissure can only be determined by
the following tests: (a) It must cut right through the entire thickness of
the operculum and reach the furrow surrounding the island of Reil; (b) It
must be a primitive deficiency in the opercular covering of the insula ; (c)
It must lie in front of the inferior prsecentral sulcus.

9. A single anterior limb of the Sylvian fissure was present in 30 per
cent, of the hemispheres examined ; the two anterior limbs quite distinct
and separate were present in 37'5 per cent. ; the Y-shaped condition of
the two limbs was present in 32'5 per cent.

10. The two orbital limbs of the Sylvian fissure cannot be regarded as
belonging to the same category as the true anterior limbs. They are not
developed as primitive deficiencies in the orbital operculum.

11. The posterior insula is not connected with the extremity of the
temporal lobe, as Eberstaller has asserted, but with the limbic lobe.

12. On the surface of the foetal insula there appear three radial furrows
which correspond in every respect with the three radial " Primarfurchen "
on the outer surface of the mantle (viz. the fissure of Rolando, the inferior
prsecentral sulcus, and the vertical limb of the intra-parietal sulcus). The
radial furrows on the insula clearly belong to the same fissural system and
intermediate links between the three radial fissures on the outer surface of
the hemisphere, and the three radial fissures on the insula may exist in the
form of secondary sulci cutting the margin of the fronto-parietal operculum.

13. The fissure of Rolando is clearly the proper boundary of the
frontal lobe. Above, it is only separated from the calloso-marginal fissure
which bounds the lobe internally by a narrow, but superficial gyrus ; below,
the inferior transverse furrow of Eberstaller acts as an intermediate link
between it and the sulcus centralis insulse. The sulcus centralis insulse
and the calloso-marginal sulcus are brought into close relationship at the