Edward Anthony Spitzka 35 
Lrerr HEMICEREBRUM. 
THE INTERLOBAR FissuRES.—The Sylvian Fissure and its Rami.—The sylvian 
fissure proper is 4.5 em. in length. It is quite shallow cephalad, as the 
following measurements of the depth will show: Presylvian depth, 10 
mm.; medi-sylvian depth, 18 mm.; post-sylvian depth, 25 mm. 
Its course approaches ‘the horizontal very nearly, and it is a little more 
tortuous than is common. 
The basisylvian, measured from the temporal pole, is 20 mm. in depth. 
The presylvian is simple, and 14 mm. in length. The subsylvian is also 14 
mm. long and ends in a bifurcated manner. The episylvian is 25 mm. in 
length and anastomoses with the intermedial. The hyposylvian is dis- 
tinct and 14 mm. in length. 
The Central Fissure—The central fissure, 10.5 em. in length, presents the 
usual five alternating curves. It does not anastomose with any other 
fissure. Its dorsal end crosses the dorsi-mesal margin to appear for about 
1 em. on the mesial surface of the paracentral gyre. The dorsal third of 
the fissure, as will be noted in Figure 3, approaches the intercerebral cleft 
in a perpendicular manner, not, as is usual, at a distinetly acute angle. 
From the fissure spring two short caudal and two cephalic rami. 
Occipital Fissure—The occipital fissure has a mesial length of 3.4 cm., 
and a dorsal length of 2.2 em. On the mesial surtace the fissure describes 
a compound curve, and anastomoses deeply, cephalad, with what possibly 
corresponds with Wilder’s adoccipital. A superficial anastomosis is 
effected with the cuneal fissure. Dorsally the fissure ends in a simple 
manner, limited by a well-developed paroccipital gyre. 
Calcarine Fissure—The calearine fissure is 3 em. in length, and is limited 
dorsally by a slightly depressed transcalcarine isthmus. The postcalcar- 
ine passes well upon the occipital polar surface, attaining a length of 4 
em., and bifurcating laterally. 
The occipito-calearine stem is 3.2 em. in length and joins both the 
occipital and calearine fissures at considerable depth. 
FISSURES OF THE FRONTAL LOBE (LATERAL SurrAcE).—Precentral Fissural 
Complexr—The three integral parts of this complex, namely the super- 
central, precentral and transprecentral, anastomose to form a continuous 
fissure springing out of the sylvian and passing without interruption to 
the dorsal margin. The supercentral is of irregular zygal shape, and is 
confluent with the superfrontal and precentral. The precentral is tor- 
tuous and ramified, and anastomoses with the sylvian by means of the 
transprecentral, and also with the subfrontal, the diagonal, and a medi- 
frontal segment. The diagonal fissure is situated between, and runs par- 
allel with the presylvian and the conjoined precentral-transprecentral. 
The diagonal does not dip into the sylvian cleft as deeply as is common. 
The superfrontal fissure springs from the supercentral, is quite long, 
and is notable for its zig-zag course and transverse ramification. | 
The marked tendency to transverse anastomosis, particularly in the 
prefrontal region, renders the interpretation of certain fissures a matter 
of great difficulty. So far as the representation of the medifrontal is 
concerned, there exist a few segments in the medifrontal gyre which de- ° 
