112 Journal of Comparative Neurology. 



cussed in part II. It would have been desirable to show stages between 

 those given in figures 43 and 44, but suitable material was not available. 



Figs, 4^, 46, 4J. Sagittal sections of the cerebellum of a human embryo, 

 No. 2862, about 10 cm. long ; poorly preserved, but shows well the relation of 

 the pileum to the paraflocculus, flocculus, and kilos. 



^'^S- 47- Shows the parafloccular sulcus, the floccular sulcus, and vermian 

 tract. 



Fig. 48. Section farther mesad than Figs. 45, 46, 47. It cuts the pedun- 

 cle and shows the pontile and caudal bundles of fibers which stream up into 

 the pileum ; also the corrugations due to the developing sulci, the dentatum, 

 the floccular sulcus, the kilos, the lateral U-bend enclosing the parepicoele, and 

 its relation to the peduncle. 



PLATE V. 



Figs, 4g, JO, J/, Brain of a human embryo 22 mm. long. No. 2652 (x 

 about 6.7). 



Fig. 4g. Shows a slightly oblique view of the dorsal aspect, also the right 

 side of the prosencephal foreshortened. Can hardly be understood without ref- 

 erence to Figs. 50 and 51. The mesencephal shows several curious transitory 

 sulci which disappear later. The form and extent of the metatela are very ap- 

 parent as is also the in-sinking collocated with the bend of the pons. This is 

 indicated by the darker transverse shading and is marked est. The cestus seems 

 to be formed here. A part of the tela was destroyed in the dissection; this ex- 

 posed the metepicoele and also shows the early parepicoele. Other features 

 shown are, 



a. The dorso-cephalic rotation of the cerebellum, better seen in Figs. 

 50 and 51. 



b. Fhe relation of the tela to the kilos around its entire circumference. 



c. The lateral U-bend. 



Fig, JO. Right lateral aspect. Shows, 



a. The position and extent of the isthmus. 



b. The deckplate. 



c. The fold in the metatela. 



d. The cerebellum, the kilos, and ripa. 



e. The lateral U-bend and parepiccele, 

 /, The bend of the pons. 



g. The mesencephalic roof which is beginning to extend both cephalad 

 and caudad. 



h. The head bend and saddle cleft. 



i. The bending ventrad of the kilos along the metaccele. 



Fig. ji. Shows the same features and also the rotation of the cerebellum 

 dorso-cephalad. Compare Figs, i, 2, 3, Plate I. 



Figs. J2 and jj. Human embryo, No. 3205, 41 mm. long, (x about 6.7). 

 Shows the same features as Figs. 49, 50, 51, No. 2652, except the tela. The 

 parts are larger, the caudal fold and lateral U-bend are better developed. 



