60 A Reconstruction of the Nuclear Masses in 



of the hilum are several short and shallow furrows, all of which pursue this 

 cephalo-caudal direction. The most cephalic of these courses as a deep 

 groove upon the cephalic pole of the olive, to turn medianly in the axis of 

 the cephalic one-third of the nucleus. Lateral to this prominent cephalo- 

 caudal groove, are three short and shallow sulci running in the same direction. 

 Still lateral to these short grooves occurs the rather deep fissure which marks 

 off laterally the most inferior gyrus of the cephalic lobe on the lateral surface. 

 This sulcus ends at some distance from the center of radiation. Caudal to 

 this occur the notch and suggestive oblique furrow formed by the super- 

 ficial ending of the first transverse dorsal fissure (o), separating the cephalic 

 lobe from the ventral portion of the lateral middle lobe. From the middle 

 of the latter lobe there radiates a shallow groove, directed laterally, caudally, 

 and somewhat dorsally. Below this an interrupted shallow grooving {b) 

 marks the caudal ending of this middle lobe on the ventral surface. This 

 grooving actually continues around in the line of the second transverse 

 dorsal fissure. More caudally, the third lateral lobe presents its ventral 

 surface, cut into gyri by two small cephalo-caudal sulci and showing a marked 

 ventral prominence below. On the mesial side this lobe is separated from 

 the dorsal caudal lobe by a short cephalo-caudal furrow, occurring but 

 slightly lateral to the border of the hilum. This small caudal lobe appears 

 Y-shaj^ed on this view, the arms of the Y forming the limits of the hilum 

 inferiorly, while the stem forms the extreme caudal pole. 



The cephalic surface of the inferior olive is not shown directly in any 

 of the plates, but a very good idea of its mor]ihology may be obtained from 

 the views of the other surfaces. It is rounded, forming the cephalic covering 

 of the olivary cavity. It is rather deeply grooved by the cephalic continua- 

 tion of the ventral cephalo-caudal furrow mentioned above. Dorsal and 

 lateral to this deei)er furrow occur several superficial grooves, which divide 

 the surface into small gyri. 



The caudal surface shows little not already described from the other 

 views. The main portion of this surface is occupied by the caudal lobe which 

 forms the lower limits of the olivary cavity. This lobe, as already mentioned, 

 gives origin to a caudal spur, showing in figures 5 and 6. The superficial 

 ending of the third dorsal transverse fissure (c) also shows on the caudal 

 surface of the inferior lateral lobe. 



Mesially the hilum occupies the greater portion of the field, showing 

 about it an edge of nuclear material and within it the reverse of the con- 

 volutions, esijccially those on the dorsal surface (figure 6). The general 

 contour of the hilum, with its prominent dorsal border and its ventral border 

 retiring laterally, is very well shown in figure 6. Beginning at the cephalic 

 dorsal angle, the border of the hilum at first goes straight ventrally; it is 

 soon turned abrui)tly caudally by a caudal ])roj(>ction of the cephalic lobe; 

 then again turns ventrally and somewhat laterally to a small notch in the 



