no Journal of Comparative Neurology. 



arrangement of the parts, and the great reduction of the roof at the meson. 

 Compare Figs 4 and 6, PI. I. 



Fig. ^2. A transection through the lateral U-bend of the same specimen. 

 After the meson had been passed, the tissue was removed from the block and 

 its position changed so as to cut transections of the remainder. It shows the 

 relation of the bend to the brain tube and that of the tela to the bend. 



Figs. ^4 and ^j. Sagittal sections through the cerebellum etc., of an em- 

 bryo kitten 23 mm. long. 



Figs . jb and 27 • Sagittal sections through the cerebellum of an embryo 

 kitten a little older than the previous one. It had been partly dissected by a 

 previous observer, so that the exact length could not be determined. This 

 shows a condition which would seem to indicate that the cerebellum, after hav- 

 ing rotated dorso-cephalad, again rotates caudo-ventrad. The condition found 

 in still older embryos would appear to support this view. See Figs. 42 and 

 43, PI. IV. 



His (15, 22) holds a different view. He says that the "tela grows fast to 

 the apposed ental surface of the cerebellum." But it seems tome that the facts 

 disprove this statement. See discussion on p. 94 of text. 



Figs. J S and J g shovf transections through the cerebellum of an embryo 

 kitten 45 mm. long. 



Fig. j8. Section through the caudal part of the cerebellum. It shows, 



a. The tips of the overlying mesencephal. Compare with Figs. 6 and 

 8, PI. I. 



l>. The structure of the cerebellum as a substantial mass of alba clothed 

 with ectocinerea, forming a part of the roof of the epicoele ; it is the roof at 

 this particular point. Compare with Figs. 10 and 11, PI. I ; also with Figs. 



27, 33, 35. 37, PI- III- 



c. The epicoele and epiplexus, the metacoele and metaplexus. In this fig- 

 ure the two plexuses have no apparent connection, but they are really continu- 

 ous. The apparent independence is due to the fact that they do not lie in the 

 same plane. The same is true for the epicoele and metacoele; the section is 

 made caudad of their point of junction. 



d. The section also shows the kilos, the cestus, the floccular and parafloc- 

 cular sulci, the paraflocculus and prepileum. 



Fig. jg. Transection of the same specimen farther cephalad. The sec- 

 tion is slightly oblique ; the right side passes through the peduncle, the left is 

 just caudad of it. It shows, 



a. The epicoeles and the parepicoeles, at the left the connection between 

 the two lateral U-bends. 



b. The epiplexus. 



c. The mesencephalon with its cavity, mesocoele ; sections farther cephalad 

 show the junction of the epicoele with the metacoele. 



d. The thin roof of cephalic part of the epicoele (valvula) and a part of the 

 cephalic extension of the cerebellum, which later becomes the preramus. 



e. The cephalo-lateral extensions of the cerebellum (prepileum) clothed 

 with cinerea, while just mesad two rounded elevations appear, the cephalic bun- 

 dles, or prepeduncles. 



