440 



ANA TOMICAL TEC 113 OL OGT. 



(12) Each lateral half of the rhinencephalon consists of a Lobus olfactorius connected 

 with the presence phalon by a distinct Crus olfactorium (PI. II, Fig. 3, 4, Cr. ol.}. 



(18) Each procoelia may be subdivided, somewhat vaguely, into a central cella media 

 (PI. IV, Fig. 15, eel. m.\ and two curved prolongations, the praecornu (PI. II, Fig. 121, 

 PI. IV, Fig. 15, W,prcu.), and the medicornu (PI. IV, Fig. 15, 17, 18, men.) 



(14) Into each cornu projects a decided eminence. That of the prsecornu is the stria- 

 turn (PL IV, Fig. 15, 16, s.), a thickening of the parietes. That of the medicornu is the 

 hypocampa (PI. IV, Fig. 15, 16, hmp.), which is chiefly an involution or folding of the 

 parietes (Fig. 121). 



(15) In addition to the atrophied portions of the ccelian parietes noted in the frog, the 

 proper nervous substance of the hemisphere is abrogated along a line from the porta to 

 near the tip of the medicornu, constituting the rima or " fissure of Bichat" (Fig. 121 ; PI. 

 IV, Fig. 14, 17, -R.). Along this line enters the larger portion of the proplexus. 



(16) As in Menobranchus, there are metaplexus, diaplexus and proplexus, the latter 

 two being continuous through the intermediation of the auliplexus and portiplexus. 



(17) The surface of the cerebellum is convoluted, presenting numerous thin folds 

 (lamina} with intervening fissures (Fig. 104, 117 ; PI. I, Fig. 1, 2). 



(18) The surface of the hemispheres is also convoluted, presenting a limited number of 

 fissures arranged according to a somewhat definite pattern (Fig. 124, 125 ; PI. I, Fig. 1, 2). 

 Most of the fissures involve only a certain depth of the mass, but the F. hypocampce, " hip- 

 pocampal fissure," represents an involution of the entire thickness of the parietes (Fig. 

 121, 125 ; PI. IV, Fig. 15, 17, F. hmp.}. 



(19) With the cerebellum and hemispheres, most of the cinerea is located near or at 

 the surface, constituting a cortex (PL II, Fig. 4, PL IV, Fig. 14, 15). The extent of the 

 cortex is of course increased by the convolutions. 



Fig. 113. Ventral exposure of the cceliae ; 

 preparation No. 458, Museum of Cornell Uni- 

 versity. Compare with Fig. 110. 



Objects. To show (A) the general succession 



^ tbe coeli8e; (**) ^ ie re l ations of tne portas to 

 the aula and procrelia? ; (C) the thickness of the 

 parietes and concomitant reduction of the ccelise ; 

 (D) the undulations of the coelian roofs. 



Preparation. From the ventral aspect of a 

 well hardened brain successive slices were re- 

 moved with the large scalpel until the portce and 

 Canalis centralis were exposed. With the Char- 

 riere scalpel there were excavated successively so 

 much of the various segments as to expose the 

 entire series of ccelise, excepting the rhinoccelise, 

 the rhinencephalon having been removed. 



On the right (left of the figure) the convexity 

 of the striatum was cut off. On the other side 

 enough more of the hemisphere and thalamus 

 was removed to expose the proplexus and thus 



throw the praecornu into direct communication with the medicornu. 



Explanation. Most of the names are written in full, and the parts mentioned are 



described elsewhere. 



Cn. ce. Canalis centralis myelonis. 



FIG. 113. VENTRAL EXPOSURE OF 

 THE CCELI.E ; x 1. 



