440 



ANATOMICAL TECHNOLOGY. 



(13) Eacli lateral half of the rlunencephalon consists of a Lobus olfactorius connected 

 ■with the prosencephalon by a distinct Crus olfactorium (PI. II, Fig. 3, 4, Cr. ol.). 



(13) Each procoeUa may be subdivided, somewhat vaguely, into a central cella media 

 (PI. rV, Fig. 15, eel. m.), and two curved prolongations, the praecornu (PI. II, Fig. 131, 

 PI. IV, Fig. 15, 16, preu.), and the medicornu (PI. IV, Fig. 15, 17, 18, mcu.) 



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

 tum (PI. IV, Fig. 15, 16, «.), a thickening of the parletes. That of the medicornu is the 

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

 parietes (Fig. 131). 



(15) In addition to the atrophied portions of the coelian 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. 131 ; PI. 

 IV, Fig. 14, 17, B.). 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 

 (lamincB) with intervening fissures (Fig. 104, 117 ; PI. I, Fig. 1, 3). 



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

 fissures arranged according to a somewhat definite pattern (Fig, 134, 135 ; PI. I, Fig. 1, 3). 

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

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

 131, 135 ; 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 (PI. II, Fig. 4, PI. IV, Fig. 14, 15). The extent of the 

 cortex is of course increased by the convolutions. 



Fig. 113. — Ventral exposure of the coeliae ; 

 preparation No. 458, Museum of Cornell Uni- 

 versity. Compare with Fig. 110. 



Objects. — To show (A) the general succession 

 J^/^ ^^^^llBBBf^ i °^ *^^ coeliae; (B) the relations of the portae to 



-> ' '*^'- *^^^Js^BHfe« V the aula and procoeliae ; (C) the thickness of the 



parietes and concomitant reduction of the coeliae ; 

 (D) the undulations of the ccElian roofs. 



Preparation. — From the ventral aspect of a 

 well hardened brain successive slices were re- 

 moved with the large scalpel until the portcB and 

 Caiialis 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 coeliae, excepting the rhinocoeliae, 

 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. 



Gn. ce. — Canalis centralis myelonis. 



Fig. 



[a 



TjiyYton 

 113. — Ventral Expostire of 



THE CcELIiE ; X 1. 



