ii6 Journal of Comparative Neurology. 



a. The tree-like appearance of the cut surface. 



b. The approximately rectangular mass of alba which forms the trunk of 

 the tree; its roots, i.e:, the peduncles, do not appear in a mesal section. 



c. The two great branches, the preramus and postramus, which divide into 

 smaller branches. Beginning with the preramus, from the lower part of the 

 trunk, there arise, 



1. The lingula. 



2. In the cat and in most human cerebellums, a branch which is absent 

 from this specimen, the cephalic lobe. 



3. The central lobe forms a third branch. 



4. The remainder of the preramus forms the culmen. Inspection shows 

 this to contain four quite large branches. These four lobes constitute the 

 prevermis. 



The postramus contains six lobes ; viz., 



1. Arising from the caudal base of the trunk is the nodulus. 



2. The uvula, divided into three smaller branches. 



3. The pyramis, divided into two branches. 



4. The tuber. 



5. The cacumen, on the meson, a single twig-like branch. 



6. The clivus, branched to form two twigs. The mesal parts of these form 

 the postvermis. These lobes are separated by deep sulci, each one named from 

 the lobe which lies next caudad of it. 



d. The relative size of the pons and oblongata at the meson. 



1. Prepontile recess. 



2. Postpontile recess. 



Fig-. 68. Dorsal aspect of an embryo human cerebellum (x about 5.5). 

 The figure has been drawn from two specimens, the cephalic part from No. 

 3161, human embryo, 15.5 cm. long, female; the caudal part from A. S27, human, 

 male, 16.5 cm. long. Shows the general appearance of the developing sulci. 



I am not yet ready to discuss the disposition of the sulci, but it is inter- 

 esting to note, 



a. That the two sides areunsymmetrical and that some of the sulci overlap 

 i.e., while most of the sulci seem to rise in the mesal region, one at least 

 arises in the lateral region and extends mesad. 



b. The right side of the cacumen is furrowed in a manner different from 

 the left side ; this will be further discussed in Part II, Compare Fig. 65, PI. 

 Ill and Figs. 59, 71, 72, 73, PI. VIII. 



The position of this figure upon the plate is undesirable but unavoidable. 



PLATE VIII. 



Figs. 6<p, 70, Cerebellum of a human embryo, No. 2947, male, 15 cm. 

 long (x 6.7). The preramus and prepileum are foliated, but the postpileum 

 on each side is smooth. 



Fig. 6g. Dorsal aspect. It shows, 



a. General regions. 



