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Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 153

its length lies in front of the suture. This portion of the fissure is seen in
the figure.

3. Girl, eleven years old (fig. 9). — Both ascending and horizontal limbs
present on the outer face of the hemisphere. The ascending limb is
short, and is concealed in the figure by the coronal bar of bone. Its base
lies immediately behind the suture, whilst the remainder of the fissure is
placed immediately subjacent to the coronal line. The horizontal limb lies
higher than in any of the preceding heads. It arises immediately behind
the coronal suture, and then proceeds forwards under cover of it to end, a
short distance above the line of the spheno-frontal suture. The termination
of this fissure is seen in the figure.

Children from four to five years old.

Three children of this period have been studied with the view of determining
the topography of the anterior limbs of the Sylvian fissure. The
heads of these are figured in Plate vi. (figs. 6, 7, and 8).

1. Boy, four years old (fig. 7).—Single anterior limb alone present.
This is placed very far back ; indeed its base is 10 mm. behind the coronal
suture. From this it ascends upwards and forwards, and its extremity lies
subjacent to the coronal suture close to the stephanion.

2. Girl, four years old (fig. 6).—The two anterior limbs present the
Y-shaped condition, and are seen in the figure. The stem of the Y, with
the ascending limb, extend, very nearly perpendicularly upwards, and is
placed 8 mm. behind the coronal line. The horizontal limb of the Y
stretches horizontally forwards, and crosses subjacent to the coronal line
immediately below the stephanion, and 19 mm. above the level of the
upper border of the great wing of the sphenoid.

o. Boyj five years old (fig. 8).—In this head the horizontal limb is on
the orbital face of the hemisphere. The ascending limb, with the exception
of the base which lies behind the coronal suture, is covered by the coronal
bar of bone. It is crossed a little above its middle point, and at the level
of the stephanion by the coronal line.

ROYAL IRISH ACADEMY.--CUNNINGHAM MEMOIRS, NO. VII. [201