Stroud, Mammalian Cerebellum, II3 



Fi^. ^4. Transection through the epencephal of a human embryo 39 mm. 

 long, No. 2139, (x 6.7). Shows very clearly, 



a. The thin deckplate not yet obliterated. 



b. The cerebellum as two thickened masses forming the lateral parts of 

 the roof. 



c. The epicrele and its lateral extensions the parepicceles. 

 (/. The kilos. 



e. The tela and epiplexus. 



f. The caudal fold. 



g. The transverse furrow in the metacoelian floor caused by the bend of 

 the pons. 



Fig. jj. Mesal aspect of the epencephal of a human embryo, No. 2, 22 

 mm. long, (x about 6.7). ShoM's the cerebellum as a fusiform mass lying in the 

 lateral part of the roof and twisted somewhat so as to conform with the general 

 shape of the epencephal at this period of development. The other features 

 need no further explanation. 



Figs. j6 and ^y. Cerebellum of a human embryo. No. 2926, 60 mm, long 

 (x about 6.7). 



Fig. j6. Dorsal aspect, shows a very interesting stage in the development 

 of the cerebellum. It looks as though a ventro-caudal rotation from the posi- 

 tion shown in Figs. 50, 51, 52, had taken place. Compare Figs. 31, 35, 36, 37, 

 PI. Ill, and Figs. 42, 43, PI. IV. I have thus far failed to obtain specimens 

 between 41 and 60 mm. in length. The examination of such specimens would 

 probably show whether such rotation does or does not occur. The specimen 

 also shows, 



a. The caudal projection of the mesencephalic roof. It differs from 

 the conditions seen in the cat where the mesencephal is notched or heart shaped; 

 here the reverse is the case. 



b. The floccular sulcus which begins in the lateral region. 



c. The kilos, the tela, the cestus, and a mesal transitory sulcus in the 

 mesencephalon. 



Fig. 57. Shows the left lateral aspect and practically the same features 

 as 56 ; also, 



a. The peduncle of the cerebellum. 



b. The pontile flexure. 



c. The crus and the overlapping caudal margin of the cerebrum. 



PLATE VI. 



Figs, jc? and ^g. Cerebellum of a human embryo. No. 3348, 80 mm. long 

 (x about 6.7). 



P^S- 5^- Shows the dorsal aspect, 



a. The mesal part is still depressed and thin ; no sulci have as yet appeared 

 upon it. 



b. The lateral parts, pilea (so-called lateral lobes), are large subspherical 

 masses. Their increase in size from now on is quite rapid. 



