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Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 87

Pansch* considers it a requisite that the anterior limb should cut right
through the operculum. Giacomini f and Eberstaller J add a still further
requirement, viz. that the incision in the operculum should be so complete
that it should reach the furrow surrounding the island of Keil. We hold
to the latter definition, but would add two further essentials, viz.—(1) that
it is a necessary character of an "anterior limb," that it be a primitive
deficiency in the opercular covering of the fossa of Silvius, and not a cleft
subsequently developed ; and (2) that it should lie in front of the inferior
prsecentral or prserolandic sulcus. With reference to this last requirement
we may remark that Broca has very properly pointed out the important
relations which the " anterior limbs " present to the inferior frontal convolution
. In fact he states that they are the result of the great development
acquired by this convolution. If we regard, therefore, an offshoot of
the Sylvian fissure which cuts into the base of the anterior central convolution
an "anterior limb," we strip it of one of its most pronounced
characters. But this last part of the definition which we have advanced
only comes into play in our determination of what is, and what is not, an
" anterior limb " in the anthropoid ape. In all probability it would not be
necessary were we familiar with the development of the hemisphere surface
in the ape, because an "anterior limb" placed behind the inferior prsecentral
sulcus is not likely to be developed as a primitive deficiency
in the operculum.

Broca § has undoubtedly the credit of having first accurately enunciated
the fact that we must recognize two anterior limbs of the Sylvian fissure,
viz. an anterior ascending and an anterior horizontal. He is wrong,
however, in so far as he insists upon their tbeing absolutely constant in
the human brain, except in the case of imbeciles, idiots, and microcephalic
individuals. It is true that he subsequently modified this statement to a
a slight degree. Thus, in the same periodical, in 1883, he writes : " The

* "TJeber die typisclie Anordnung der Furchen und "Windungen," &c. &c, Archly fur
Anthrop., Dritter Baud, p. 235, 1869.

f Varieta della circonvoluzioni cerebrali dell' uomo. Torino, 1882.
J Das Stiruhirn, p. 17. Wieii und Leipzig, 1890.

§ "Etude sur le cerveau du gorille," Revue d'Anthrop., 1878, 2e. Serie, p. 1.