484 ANA TO MIC A L TE CENOL OGT. 



§ 1383. Postcommissura (as.), pcs.—Yi^. Ill, 113, 117; PI. II, Eig. 4; PI. Ill; 

 § 1143. Gray, A, 630 ; Quain, A, II, 546. 



Snfii. — C'ommissura posterior. 



Composed of transverse fibers forming tlie caudal part of the roof of the diacoelia, and 

 thus joining the dorsal portions of the thalami. 



§ 1384. Postcornu, pcu.— Gray, A, 63.5 ; Quain, A, II, 543. 



Snjn. — Cornu posterius ventriculi lateralis, cavitas digitata. 



This caudal prolongation of the proocelia is normally present only in man, monkeys, 

 seals and cetacea. The hydrocephalous brain of a dog reported by the senior author (2.3) 

 presented a distinct postcornu, so that perhaps it may be regarded as normally rudimentary 

 or undeveloped rather than totally absent in the ordinary mammals. 



§ 1385. Postgeniculatum, 'pgn.—¥\g. 118 ; PI. Ill, Fig. 7-11; § 1144. Gray, A, 631 ; 

 Quain, A, II, 553. 



Syn. — Corpus geniculatum internum. 



The elevation at the side of the diencephalon, between the Tractus opticus and the 

 cimbia. It is proportionally much larger in the cat than in man. 



§ 1386. Postopticus, pop.— Fig. 114; PI. II, Fig. 3; PI. Ill, Fig. 7-9; PI. IV, Fig. 

 18, 19 ; § 1143. Gray, A, 631 ; Quain, A, II, 551. 



8yn. — Testis cerebri, corpus bigeminum posterius, one of the corpora quadrigeminai 

 caudal lobe of the mesencephalon. 



The marked elevation just cephalad of the cerebellum and valvula. 



§ 1387. Postpedunculus, vpd..—% 1141 ; Gray, A, 635 ; Quain, A, II, 516. 

 Byn. — Processus e cerebello ad medullam oblongatam ; restibrachium (Spitzka, 7, 165). 

 The fibrous fasciculus passing from the dorsal aspect of the metencephalon dorso- 

 cephalad to the cerebellum, mesad of the medipedunculus. 



§ 1388. Praegeniculatum (Corpus), prgn.—Fl. Ill, Fig. 7-9 ; § 1144. Gray, A, 631 ; 

 Quain, A, II, 553. 



St/n. — Corpus geniculatum externum. 



There seem to be no distinct lines of demarcation between the Tractus opticus, the 

 praegeniculatum and the thalamus. 



§ 1389. Postperforatus (Locus), {az.),ppf.— Fig. 116, 118 ; PI. II, Fig. 3 ; PI. Ill, Fig. 

 11. Gray, A, 631 ; Quain, A, II, 535. 



Syn. — Locus perforatus posticus, pons Tarini. 



A small triangular area overhung by the albicantia, and presenting a few pores for the 

 transmission of vessels. It is apparently smaller than in man. 



§ 1390. PfEecommissura (az.), prcs.— Fig. Ill, 113, 117 ; PI. II, Fig. 4 ; PI. IV, Fig. 

 14, 16, 17 ; §§ 1067, 1153. Gray, A, 630 ; Quain, A, II, 546. 



Syn. — Commissura anterior cerebri. 



At the meson this commissure is a subcylindrical fibrous fasciculus just cephalad of 

 the ColumniB fornicis. It expands laterad and reaches the striata and Crura olfactoria, 

 which it thus connects across the meson. In man, according to Meynert (Strieker, A, 680), 

 the connection of the olfactory lobes with the commissure is slight. 



§ 1391. Praecornu, prcu.—Fig. 113, 130; PI. IV, Fig. 15, 16, 18, 19 ; § 1149. Gray, 

 A, 635; Quain, A, 11,541. 



Syn. — Cornu anterius ventriculi lateralis. 



The cephaHc portion of the proccelia. It is quite high, but compressed, the striatum 

 projecting into it. The ventro-cephalic end narrows suddenly to become continuous with 

 the rhinocoelia. 



