AMERICAN NEGRO BRAIN 209 
over half of the hemispheres is too large to be passed over as a 
sulcus intermedius primus. This sulcus is undoubtedly a 
fissural representation of a prominent growth in the inferior 
parietal region. It has only a secondary morphological value, 
for it is absent in some of the hemispheres. It is noteworthy 
that in those hemispheres in which it is absent, the fissuration 
of the still prominent inferior parietal region is accomplished 
by one or two unusually prominent sulci intermedii in the pos- 
terior parietal region. From this it is safe to conclude that the 
presence of one or more very prominent accessory sulciin the 
inferior parietal region is a normal feature of the Negro brain, 
and that the greatest tendency, amounting to at least 75 per 
cent, is towards the development of this sulcus in the region 
between the posterior extremity of the Sylvian fissure and the 
ramus ascendens of the sulcus temporalis superior. ° When the 
sulcus is present its superior extremity is surrounded by a distinct 
and additional arcuate gyrus of the lobulus parietalis inferior, 
situated between the gyrus marginalis and the gyrus angularis. 
Probably this sulcus has been figured by Smith (’06, fig. 2). 
Other minor variations have been noted in the preceding 
section but they are not of sufficient value to be reviewed. 
We have refrained from the tabulation of characters supposed 
to represent Simian features, and which have been employed in 
some of the more recent studies. Many of these variations are 
due almost entirely to mechanical influences of a nature we can 
only suspect and are consequently unreliable as evidences of 
inferiority. »° 
Some space has been devoted to the consideration of the 
occurrence of a detached portion of the fissura rhinalis, most 
frequently in communication with the sulcus collateralis. This 
reveals the fact that the apparent entire absence of the fissura 
rhinalis is in reality merely an interruption of this fissure by the 
superficial bridging gyrus fusiformis-rhinencephali. Therefore 
the degree of development of this fissure should be judged, not 
by the prominence of the incisura rhinalis, but by the prominence 
of the detached element of the fissura and the width or promi- 
nence of the bridging gyrus. 
