Stroud, Mammalian Cerebellum. 87 



arches over the epicoele. At the right and left it bends over 

 into the epcoeHan floor. Cephalad it is separated from the mes- 

 ocoelian roof by a constriction, and becoming thinner caudad, 

 merges into the metatela. From the caudal aspect, because of 

 the wedge-like cephalic point of the metatela, this lamina looks 

 hke a pair of lateral plates. This plate may be called Kleinhirn- 

 lamella, (lamina cerebelli) because it is the proton (Anlage) of 

 the future cerebellum. The cerebellum is formed from this 

 lamella in the following manner : the cephalic portion of this 

 lamella thickens, while the caudal edge at the transition into 

 the metatela becomes sharpened," 



This thin margin bends ventrad and there results a plait- 

 like folding in along the caudal edge of the ' Kleinhirnlamella, ' 

 The cephalic, thickened part of this transverse plait (or fold) is 

 the proper proton (Anlage) of the cerebellum. The caudal 

 is the " hinteres Marksegel, ' (velum medullare posticum, v. 

 Tarini) " or what the writer calls kilos. From his own ob- 

 servations the writer can not accept this view as to the develop- 

 ment of the cerebellum. 



1877. Alix (i) pubhshed a paper on the fetal brain. 



1878. Kolliker (20, 537) says, "The cerebellum is de- 

 veloped as a thickening of the cephalic part of the roof of the 

 epencephal (Hinterhirn), which soon assumes the form of a trans- 

 verse plate. From the lateral aspect it looks as though it bent 

 around the epencephal (Hinterhirn)." 



1884. Wilder (35, 179; 37, 125) figures the cerebellum 

 of a human embryo in which the lateral parts are massive, the 

 mesal region is thin and presents a wide groove upon the dorsal 

 surface. It is probably a little older than the embryos shown 

 in Figs. 54 and 56, PI. V. 



1890. Hertwig (18, 360) says, "The wall of the fourth 

 brain vesicle undergoes a considerable thickening in all of its 

 parts, and surrounds its cavity in the form of a ring, differen- 

 tiated into several regions. The floor furnishes the pons. From 

 the lateral walls arise the peduncidi cerebelli adpontem. But it is 

 the roof that grows to an extraordinary extent and gives to the cer- 

 ebellum its characteristic stamp. At first it appears as a thin 



