Edward Anthony Spitzka 49 
The superfrontal gyre is especially broad in the prefrontal region, and 
more or less regularly divided into two longitudinal tiers by two para- 
mesial fissural segments. Between these two are a triradiate and also a 
zygal segment; still further cephalad there are numerous transverse tri- 
radiate and zygal pieces which make this portion of the gyre of an ex- 
ceedingly complex configuration. 
The medifrontal gyre is massive, tortuous and distinetly divided into 
two tiers by a long medifrontal fissure. 
The subfrontal gyre, while small, is well convoluted, and in general €x- 
hibits most strikingly the tendency of fissures and ramifications to 
assume a transverse direction. 
Merstan SurrAcre.—The mesial surface of the superfrontal gyre is broad 
and traversed by a large number of radiating fissures and rami. The 
dorsi-mesal margin is particularly marked by numerous fissural segments. 
The paracentral gyre is of moderate size, of simple form, marked merely 
by a short longitudinal intraparacentral, and slightly indented in its dorsal 
margin by the central. 
ORBITAL SURFACE.—On the orbital surface may be distinguished a post- 
orbital portion, and several sagittal preorbital gyres. The mesorbital 
gyre is very narrow. 
FISSURES OF THE PARIETAL AND OccrpiIrAL LOBES (LATERAL SURFACE).— 
The Postcentral Fissural Compler.—In this hemicerebrum, the postcentral and 
subeentral are combined to form a continuous fissure, attaining a length 
of 8.5 em. Dorsally, the fissure bifureates, embracing the gyre indented 
by the caudal limb of the paracentral. The caudal limb of the postcentral 
is joined by a transparietal piece. In all, five additional rami spring from 
the combined fissure. A vadum separates it from the parietal; another 
from the central. | 
The parietal, cephalad, is ramified. A narrow isthmus separates it from 
the supertemporal. Caudad it anastomoses with the cephalic limb of the 
paroccipital. A deep fureal ramus passes into the parietal gyre. 
A transparietal has been described as confluent with one of the post- 
central dorsal limbs; another fissure, also confluent with the postcentral, 
ruus somewhat parallel with the parietal. 
A quadri-radiate fissure lies in the marginal gyre, just dorsad of the short 
episylvian. A true intermedial does not seem to be present. 
The paroccipital is of the usual zygal shape, with its cephalic stipe pass- 
ing into the cuneolus, i. e., between the occipital and adoccipital fissures. 
Laterad in the angular gyre, just caudad of the supertemporal and the 
cephalic paroccipital ramus, there is a fissure, 3.5 em. in length, whose walls 
are markedly inclined caudo-ventrad. If this fissure represents, as it 
probably does, a segment of the exoccipital, we have here the formation 
of a partial occipital operculum. There are other zygal pieces on the 
lateral surface apparently in the course of the primate exoccipital, as well 
as numerous fissures in the angular gyre and occipital region. 
MESIAL SuRFACE.—The precuneal fissure is of irregular zygal shape. 
The‘ ventro-cephalic limb is unusually long. It does not anastomose with 
other fissures. ; 
4 
