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Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 89

Ecker* also only recognizes one anterior limb, the ascending, and
although he figures the development of both, he does not refer to the
anterior horizontal limb (vide his fig. 3, PL iv.).

Hervdf repeats in every particular the description of Broca, and lays
stress upon Broca's statement that one of the two limbs, viz. the anterior
horizontal, is constant and essential, whilst the other, the ascending, is
only accessory. As we have seen, the development of the region does not
bear out this view, because when one limb only is present, it is neither the
ascending nor the anterior horizontal, but a compound of both. It is
upon the condition of the Sylvian fissure in the orang and chimpanzee that
these authors found their opinion as to the predominant importance of the
anterior horizontal limb. It will be our duty later on to show that the
arrangement in these apes can bear another interpretation.

ZuckerkandlJ has examined the two anterior limbs of the Sylvian
fissure in a series of fifty hemispheres, but the conclusions which he draws
from these are hardly justified by the facts, because he includes in the list
fissures which did not completely cut through the operculum, and further,
he appears to take for granted, as Broca also did, that when one anterior
limb alone is present, this is the anterior horizontal limb. The following
is a summary of his results :■—

Ascending limb.—(a) In twenty-nine cases it cut right through the
operculum ; (b) in twenty-one cases it only cut partially into the
operculum. §

Anterior horizontal limb—(a) In thirty-six cases it was normal; by this,
I presume, he means that it penetrated right through the operculum
; (b) in fourteen cases it was absent or represented by a
mere notch.

* "Zur Entwicklungsgeschichte d. Eurchen u. 'Windungen d. Grossliirn-Hemispharen,"
Archiv f. Anthrop., Dritter Band, 1869.

f La circonvolution de Broca. Paris, 1888.

\ " Beitrage zur Anatomie dcs menschlichen Korpers," Ueber den Einfluss des Naht-
wachsthumes und der Schadelform auf die Bichtung der Genirnwindungen.—Medizinische Jahr-
biicher, 1883, in. imd it. Heft., p. 446.

§ When studying the development of the anterior limbs of the Sylvian fissure I frequently

koyal irish academy. — cunningham memoirs, no. yii. ["12"]