( ^^ ) 



since in three cerebella of this stage 1 tbiuul both of them already 

 present in each (total length of the foetus 8 to 10 cm.). The anterior 

 groove is the sulcus primarius (1), the typical principal groove, easily 

 recognised in every nianmuilian cerebellum, sepai'ating the two lobes 

 of the cerebellum, the lobus anterior and lobiis poslerioi'. Tiie posterior 

 groove is the sulcus uvulo-nodularis {iiii/u') (sulcus postiiodulai-is of 

 Elliott Smith, sulcus praeuvularis of Zikhk-n, Fissure IV of Charnock 

 Bradley). It borders the nodulusin front, i.e. in the direction of 

 the mesencephalon. Between these grooves a still shallow depression 

 is visible on the upper part of the posterior j»lane, the lii-st indication 

 of the fissura secunda (Elliott Smith, niihi, sulcus inferior anterior 

 of Ziehen, fissure d of Charnock BRADiiEv). The cerebellum, seen at 

 this stage from behintl, is somewhat biscuilshaped (tig. 6) and lies with 

 the front planes of its lateral parts against the occipital poles of the 

 hemispherical vesicles. Besides the two mentioned gi'ooves, proceeding 

 from the median line, the cerebellum possesses at this stage already 

 a sulcus which is bilaterally symmetrical and lies at a short distance 

 of the margo myelencephalicus. This groove {p), which develops in 

 a latero-inedial direction is the hoinologon of the groove which I 

 have distinguished in the mammalian cerebellum as lissura para- 

 floccnlaris. It borders in front the already slightly prominent so-called 

 recessus lateralis. The anterior wall of this recessus lateralis has been 

 distinguished by Kölliker as gyrus chorioidcus. It seems to me that 

 the name "Gyrus floccularis" is more characteristic, since from this 

 narrow cerebellar seam which is already marked out at so early a 

 stage, the tlocculi are later formed. 



In a successive stage (Figs. 7 and 8) the sulcus primarius (1) has 

 become deei)er and the tissura secunda (2) has become a distinct 

 grooxe ; moreover a first secondar}' groove has arisen in the lobus 

 anterior. Later this lobus is separated into four small lobes by three 

 grooves; I have not been able, however, to make out which of 

 these three is the first to appear. That the sulcus in the. lobus anterior, 

 seen in tigs. 6 and 7, which is first in appearing, is really the 

 groove, distinguished by Elliot Smith as sulcus praeculminatus, I 

 have not been able to confirm, while also from a comparison of my 

 human cerebella of this stage witli corresponding figures given by 

 Charnock Bradley for the rabbit and pig, it appears that this first 

 groove lies in the lobus anterior of man farther away from the sulcus 

 primarius than with the two animals mentioned. So I camiot decide 

 whether this first groove in the lobus antei-ior in man is homologous 

 with the "Fissure 1" of Charnock Bradley. Also in the lobus 

 posterior a new groove has appeared in the median line, between 



