////: r/:.Y77/.i/. .i\/> ,,r mi: 



prominent than in animals, and are also dittingaiahed l>y tin- \>r> >< -M.-,- f .f a 

 nucleus in tlieir interior. The medulla obkmgaia of Man baa not the transvene band, 

 behind the pons Varolii, which we described in the Horse (l-'i^. :>:;:: . 



With regard to the iMlmms proper, it contains the part.- in frnt of the medulla 

 oblongati alnady studied in the domesticated animals. Tin /.;/.- l"/W// is\.i\ lar ; 

 the crura cerebri are separated from each other by a groove at the l.ottinn >( which are 

 several small openings. The jum-th i; ntrirl, is <li,-|i. j.- hindered |.\ \M-ll-develn|.ed 

 corpora regtiformia, and inclosed posteriorly and laterally l>y tin i-nln x // 7Vir/ (r.lnm 

 innlnUare postering). On its floor are remarked transverse stihc (///,.: //<('*,-, ; -s.-< ) i.aim d 

 the ?>or6 o/ </ie calamus scriptoriut, which nrc also found in the \)< x. The f<>//.- an- 

 smaller than the nates; but the difference in their volume is less considerable than 

 between Solipeds and liuminants. Their structure is already known. 



ARTICLE III. THE CEREBELLUM. 



The cerebellum, or posterior enlargement of the cncephalon, is tho 

 single mass supported by the isthmus, separated from the cerebrum by tin; 

 transverse partition constituting the tentorium cerebelli, and lodged in tlm 

 posterior compartment of the cranial cavity, which almost exactly gives tho 

 measure of its volume. 



1. External Conformation of the Cerebellum. 



The cerebellum, isolated by dividing its lateral peduncles from the 

 medullary prolongation on which it is fixed, presents the form of an almost 

 globular mass, slightly elliptical, elongated transversely; while its external 

 surface is furrowed by a great number of sulci, tho two principal of which 

 (sulci Jiorizontalis) pass in a circular manner on each side of the middle line 

 around the organ, dividing it into three lobes a middle and two lateral. 



The three lobes of the cerebellum are not always readily distinguished 

 from each other, in consequence of the shallowness and irregularity of the 

 two sulci separating them. We will, nevertheless, study them in 

 succession, and afterwards examine, in a general manner, the furrows on their 

 superficies. 



Middle lobe (Fig. 321, 2). This has been compared to a silk-worm 

 rolled in a circular manner around the middle portion of the cerebellum, 

 and whose two extremities are joined, without being confounded, below the 

 inferior face of the organ. 



This vermicular disposition is not well defined in the middle and 

 superior portion of the cerebellum, where this lobe is always more or less 

 subdivided into large multiple and irregular lobules ; but it is better 

 observed before and behind, in those points which correspond to tho two 

 extremities of the animal selected as a term of comparison. There may 

 bo remarked two longitudinal eminences transversely annulated on their 

 surface, and curved beneath the cerebellum in such a way as to come in 

 contact with each -other. These eminences constitute tho anterior and 

 posterior vermiform processes. Their extremities are lodged in tho fourth 

 ventricle, whose roof they concur in forming. 



On the anterior vermiform process the posterior border of tho valve of 

 Vieufiseus is inserted. 



The posterior vermicular process also receives tho insertion of a valvo 

 already mentioned, and which must be again briefly referred to. This valve, 

 described for tho first time by M. Renault, 1 forms a lamina of a certain 

 thickness stretched above the calamus scriptorius. It has exactly the 

 triangular form of this space, and presents a superior face covered by the 



( l The late eminent veterinary teacher imd director of tho Alfort School.) 



