SYXOXYJfS AND REFERENCES. 485 



1292. Praepedunculus, prpd. 1141. Gray, A, 635: Quain, A. II, 576. 



Syu. Pedunculus cerebelli superior, processus e cerebello ad testim, crus cerebelli 

 superius, testibracbium. 



The prapedunculi extend from the cerebellum to the base of the postoptici, and form 

 the walls of the cephalic and longer part of the epicoelia. 



1293. Praeperforatus (Locus), prpf.Fig. 116, 118 ; PI. II, Fig. 3 ; PI. Ill, Fig. 11. 

 Gray, A, 621 ; Quain, A, II, 536. 



Syn. Locus perforatus anterior s. anticus, anterior perforated space. 



The irregular area just cephalad of the chiasma. In man it is comparatively small, but 

 in the cat it is larger and presents two quite distinct portions, a cephalic which is more 

 or less elevated and often distinctly marked by longitudinal furrows and ridges, and a cau- 

 dal which is smaller, depressed, and smooth excepting for the vascular perforations which 

 characterize the entire area. The two divisions are hence named Portia prominens and 

 Portia depressa. Between the depressed portions is the slight gray elevation of the terma, 

 forming part of the floor of the Recessus opticus. 



1294. Proccelia, prc. Fig. 110-113 ; PI. IV, Fig. 15, 16, 18, 19; 1064. Gray, A, 

 624 ; Quain, A, II, 539. 



Syn. Ventriculus lateralis, ventriculus tricornis, lativentriculus, first or second ven- 

 tricle. 



The lateral cavity of the prosencephalon, communicating through the porta with the 

 aula and thus with its platetrope, and with the mesal series of coeliae. Cephalad it opens 

 into the rhinoccelia. 



1295. Proplexus, prpx. Fig. 113, 121 ; PI. IV, Fig. 15, 18 ; 1066, 1149. Gray, 

 A, 627 ; Quain, A, II, 545. 



Syn. Plexus choroideus ventriculi lateralis. 



The larger part of this plexus of the procrelia is formed by the intrusion of the velum 

 or of vessels thereof between the fimbria and the Sulcus limitans so as to appear, still cov- 

 ered by endyma, in the medicornu. Its length thus coincides with that of the rima. 



A smaller portion of the proplexus projects laterad into the praecornu, as shown in PI. 

 IV, Fig. 18. 



Respecting the continuity of the endyma upon the proplexus, see Todd (A, III, 704) ; 

 Balfour(A, II, 364, Fig. 260, 261) ; Mivart (B, 267) ; Gray (A, 627) ; Quain (A, II, 546). 



1296. Prosencephalon (as.), pren.Fig. 110-118 ; PL I, Fig. 1, 2 ; PI. II, Fig. 3, 4 ; 

 PL III, Fig. 5, 6, 11. 13 ; PL IV, Fig. 14-20 ; 1061, 1138, 1145. Gray, A, 111 ; Quain, 

 A, II, 759. 



Syn. Cerebrum, hemisphserae, forebrain. 



The cavities of the prosancephalon are the aula, the portce and the proccelice. 



% 1297. Pseudocoelia (az.\ psc.%$ 1064, 1137 (4), 1162 (2). Gray, A, 627 ; Quain, A, 

 II, 543. 



Syn. Ventriculus quintus, ventriculus septi pellucidi, ventriculus Sylvii, incisura 

 septi, sinus septi pellucidi, fifth ventricle. 



In man the mesal surfaces of the hemispheres between the callosum and fornix are 

 separated by an interval, the " fifth ventricle." In the cat the two hemisepta are in con- 

 tact, and the pseudocoelia does not exist. 



1298. Pyramis, py. Fig. 116 ; PL II, Fig. 3, 4 ; 1140. Gray, A, 612 ; Quain, A, 

 II, 504. 



Syn. Corpus pyramidale, prepyramid, ventripyramid, anterior pyramid. 



At the side of the meson, iust caudad of the pons and extending a little caudad of the 



