^Z JorHNAl. (>!■ C(>MV.\RATl\K N KlMit^T-OGY . 



that I have studied, it is longer than wide (Pate V, Fig. 6). 

 Connections. — The epencephalon is connected to the 

 metencephalon by the crura ccribelli. 



EXPLANATION OF TABLE IV (SEE P. S4) . 



'■ Length " is a contraction for " Ratio of the length of the c pen- 

 ce flialou to the length of the brain. 



"Breadth " is a contraction for " Ratio of the greatest width of the 

 epenceplnilo)! to the length of the brain." 



" Depth " is a contraction for " Ratio of the depth of the cpeucep- 

 a/oii to the length of the brain. 



"The length of the brain is the distance between the cephalic por- 

 tion of the prosencephalon and the centre of the rhombic depression 

 that lies immediatelj' caudad to the twelfth nerve root. 



The length of epencephalon used is the distance between the apex 

 of the caudal V of the prosencephalon and the caudad extremity of the 

 epencephalon. 



All ratios are expressed in hundredths of the length of the brain. 



METEXCEPHALOX. 



The metencephalon lies beneath the epencephalon and is 

 connected with it by the crura cerebelli. The metencephalon 

 is intimately connected with the diencephalon. 



Form. — In form the metencephalon is a sub-rectangular 

 prism, all of the exposed faces of which are feebly convex. 

 Near the caudal extremity of the metencephalon, its lateral 

 and ventral faces slope, abruptly, ento-caudad, to the myelon. 

 On the ventral surface, at the union of the metencephalon 

 and myelon, there is a small diamond-shaped depression 

 (Plate V, Figs. 7, 13). 



.Surface. — The entire surface of the metencephalon is quite 

 smooth. There is no external indications of either pons or 

 pyramids. On the ventral surface, however, there is usually 

 a faint indication of a mesal fissure (Plate \', Figs. 7, 13). 



Proportions. — The metencephalon is usually from one-half 

 to three-fourths as deep as wide, and about as wide as long 

 (see Table \). 



Fourth ventricle. — As usual, the metencephalon contains 



