AMERICAN NEGRO BRAIN 187 
The study of a series of Negro brains in comparison with a 
series of Caucasian brains should present the most promising 
field for the establishment of differentiating characters, since 
the two races are apparently so remotely related. Numerous 
isolated observations have been made on the Negro brain, but 
the literature still lacks a detailed presentation of a series of such 
brains. The following report is offered with the hope of, in a 
measure, supplying this lack. We have not attempted to 
establish a group of supposed inferior characters but simply to 
record the arrangement of the gyri and sulci in a series of brains 
and as far as possible interpret the growth process in different 
areas with the resulting influence on the convolution pattern. 
DESCRIPTION 
In the following description the terminology suggested by 
Retzius will be used except in the occipital region, which in the 
Negro brain seems to lend itself better to the more recent usage 
of Elliot Smith. 
The fissura Sylvit propria is remarkable for its very straight 
course. In the majority of hemispheres there is no pronounced 
upturning at the posterior end. In all but one hemisphere of 
the series a terminal bifurcation can be identified, but in a few 
one ramus is very rudimentary. Three hemispheres represent 
a communication between the ramus posterior descendens and a 
contiguous sulcus. Such connection is obliterated in the other 
brains by the development of a very distinct posterior operculum - 
which can be identified in 92 per cent of the series and appears 
to be a large factor in the formation of the bifurcation just 
referred to. Cunningham (’92) has noted a similar condition 
and Appleton (’10) also speaks of the ‘lingula’ in the brains of 
the natives of India. The unusual prominence of this operc- 
ulum coupled with the short fissura Sylvii may be interpreted 
as an index of the growth activity in the post-Sylvian region. 
The anterior rami of the fissura Sylvii are in many instances 
difficult to identify; one brain in particular deserves mention. 
In both hemispheres the superficial appearance is of two 
