280 t>TUI)V OF BR.'VIN'S oK SIX EMINENT SCIENTISTS AND SCHOLARS. 



Left Hemicerebrum. The Interlobar Fissures. Ihe Sylvian Fissure and if.^ 

 Rami. — The sylvian fissure attains a length of 5.9 cm., its walls are in close apposi- 

 tion, and its course is quite tortuous. Its angle with a plane passing through the 

 ventral margins of the frontal and occipital poles is 28°. Its depth at the pre-sylvian 

 point is 13 mm.; medi-sylvian depth 19 mm.; post-sylvian depth 25 mm. The pre- 

 sylvian ramus is 2.5 cm. in length and anastomoses caudally with the diagonal. The 

 subsylvian is short. The basisylvian, measured from the tip of the temporal lobe is 

 20 mm. in depth. Caudad, the sylvian terminates in the episylvian ramus 2.4 cm. in 

 length. The hyposylvian is absent. 



The Central Fissure. — Measuring with a wet string, this fissure is 11.8 cm. in 

 length ; measured with a pair of compasses, 8.2 cm., quite above the average. It does 

 not anastomose with any other fissure and has only one short caudal ramus near its 

 ventral end. The course of the fissure can be resolved into seven alternate curves, 

 instead of tlie usual five. Several interlocking subgyres may be seen in its depths 

 but there is no appreciable " central vadum." The ventral end is separated from the 

 sylvian by an isthmus 6 mm. in Avidth ; the dorsal end appears on the mesial aspect 

 for 1.5 cm. The general direction of the fissure makes an angle of 53° with the inter- 

 cerebral cleft. 



The Occipital Fissure. — Its lengtli on the meson is 2.8 cm. ; on the convex surface 

 2.3 cm. It sends one ramus into the cuneal surface and terminates on the dorsum in 

 a furcal manner, the cephalic limb communicating with the cephalic stipe of the par- 

 occipital at a depth of 8 mm. over a very narrow submerged isthmus — the reduced 

 cephalic limb of the paroccipital gyre. Notable is the obtuse angle which the fissure 

 makes with the (arbitrary) horizontal plane alluded to above ; namely 70°. In most 

 brains this angle approximates 60°. The fissure therefore does not approach the cal- 

 losum as much as is the rule, and its junction with the calcarine is effected much 

 further caudad than usual. 



The Calcarine Fissure. — The calcarine fissure describes an angular course, bend- 

 ing sharply dorsad near its junction with the occipito-calcarine stem. It terminates 

 caudally in a T-shaped bifurcation, the ventral arm of which again bifurcates. Each 

 of tliese bifurcations embraces an independent fissural segment, of which the ventral 

 one probably corresponds to the postcalcarine, "or sulcus extremus " of Schwalbe. 



The occipital and the calcarine meet at considerable depth to pass into the occi- 

 pito-calcarine fissural stem. This passes cephalad for 3.7 mm. and comes within 1 

 mm. of anastomosing with the hippocampal fissure. 



FissuRKs OK THE Frontal Loi'.e (Lateral Surface). The rrcrctUnil Flsdu.ral 

 Corwplex. — This consists of tlu-ee segments: an independent supercentral, and two 



