MAMMALIA. 



127 



large part of this surface ; it is divided into three sections, the tract of the first forms 

 the inner part of the restifonn body, after it has been joined by the anterior pedicle of 

 the cerebellum ; the tract of the second section proceeds to the oblong medulla accom-i 

 panied by the tract of the second section of the third layer; the third section 

 terminates in the median crescentic tract or belt, to pass forward round the crus, and 

 then down the oblong medulla with the first section of the third layer. The inter- 

 mediate layer has a smaller portion anteriorly, which sends its tract to the first 

 segment of the crus of the brain for the origin of the third nerve ; the larger portion 

 sends its tract down at the posterior part of the annular tubercle to receive the tract 

 of the first convolution of the intercedent region, and then give origin to the smaller 

 portion of the fifth nerve, the hard portion of the seventh and the ninth. The outer 

 layer is divided into four sections ; the tract of the first is the most anterior, it passes 

 with the median crescentic tract or belt through the crus of the brain and annular 

 tubercle exteriorly to the outer crescentic tract or belt, and through the oblong medulla 

 and spinal cord. The tract of the second section passes next, with the tract of the 

 second section of the inner layer, through the crus of the brain and annular tubercle, 

 the oblong medulla and spinal cord. The tract of the third section becomes joined 

 with the inferior pedicle of the cerebellum, and passes to the outer side of the restiform 

 body. The fourth section, arising from the posterior and inferior convolutions, has 

 its tracts concentrated in the outer crescentic tract or belt to pass forward round the 

 crus of the brain, and then descend in the median edge of the crus, the annular 

 tubercle, and oblong medulla, to the side of the deep fissure of the spinal cord. 



This description corresponds with the motive centres and tracts in the horse, and 

 with the same in simise when it is stated that the median and outer crescentic tracts or 

 belts pass by fibres through the grey matter of the striated body, before they enter the 

 crus of the brain. The arrangement in simiae corresponds with that in man, except the 

 median crescentic tract or belt, which in man is double, one part of it passing with the 

 outer crescentic tract or belt through the crus, the other part accompanying the tract 

 of the first section of the outer layer to pass through the crus and annular tubercle. 



The intermediate layer actuates muscles attached for the most part to fixed bones, 



