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Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 251

Giacomini* has stated that the sulcus prsecentralis inferior anastomoses
in 68 per cent, of the hemispheres examined, with the anterior limb of the
Sylvian fissure, and Eberstaller thinks that this may be explained by the
junction effected through the sulcus diagonaiis. This mode of union is
much less frequent in its occurrence. There are many instances, however,
in which the sulcus diagonaiis assumes a very considerable length, and

Figj. 55.—Left cerebral hemisphere from a foetus in the eighth month of development. Drawn
by the American apparatus for tracing orthogonal projections of the skull.
The dotted connexions between certain of the furrows indicate the position of deep
annectant gyri.

r.

Fissure of Rolando.

/•' •

Sulcus frontalis primus.



p. c. s.

Sulcus prsecentralis superior.

/• »»•

Sulcus frontalis medius.



h. .

Ramus horizontalis of the sulcus prsecentP
•

. Sulcus frontalis secundus.





ralis inferior.

s.2 .

. Anterior ascending limb

of the Sylvian

p. e. i. .

Sulcus prsecentralis inferior.



fissure.



i. t. .

Inferior transverse furrow of the fissure of

s.1 .

. Anterior horizontal limb

of the Sylvian



Rolando.



fissure.



whilst it keeps separate from the praecentral sulcus, opens into the inferior
frontal furrow (fig. 54, s. d.). When this occurs, the sulcus diagonaiis is
very apt to be mistaken for the sulcus prsecentralis inferior, and it is
just possible that Giacomini may have included it in his statistics as such.

* Varieta delle circonvoluzioni cerebrali dell' uomo. Turin, 1882.

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