CENTERS OF CORRELATION. 



2 55 



ventricle is much thicker than the rest and is known as the collie- 

 ular region. The portion which roofs over the optic ventricle 



Rad. 

 esenc. 



olliculus 



Lemniscus 

 system 



Arcuate fibers 



Decuss. and 

 A Nuc. tr. hab. pedunc 



Rad. mesenc. V 



olliculu 



Lemniscus 

 system 



_r. tecto-cerebel 

 tecto-cereb. tr. lobo-bulbaris 

 C 



Rad. mesenc. V, / Cor P- ^ uad - ant - 



Lernniscus 

 system 



III 



Cereb.ped. 



Fig. 127. Outline transverse sections through the mesencephalon of various 

 vertebrates to illustrate the changes of form of the tectal region. A, a cyclostome; 

 B, a selachian; C, a ganoid; D, a bony fish; E, an amphibian; F, man (after 

 Koelliker). r, nucleus ruber; 5. n., substantia nigra. 



is known as the tectum opticum. (It must be remembered always 

 that the tectum opticum is only a part of the tectum mesencephali.) 



