130 



ANATOMY OF THE CENTRAL NERVOUS SYSTEM. 



phibians and reptiles where the other ganglia of the thalamus are only 

 slightly developed relatively, or in fishes where they are placed more to 

 the ventral position, the Ggl. habenulse occnpy a position in front of all the 

 other interbrain-ganglia. When in birds and mammals the other eon- 



Fig. 79. — Horizontal section through the Gang, habenulae of a turtle: 

 Emys enrop. 



stituents of the thalamencephalon develop more and more, they press the 

 epithalamus somewhat back; so that the whole remaining part of the 

 interbrain lies between it and the forebrain. The relative location of the 

 epiphysis remains, in the meantime, unaffected. 



Fig. 80. — Sagittal section through the brain of Triton, lateral from the 

 median line, showing the Fasciculus retroflexus; also the Tr. Strio-thalamieus 

 ending in three places in the interbrain. 



The tracts which pass to the epithalamus are as constant as the develop- 

 ment. First, it always receives anteriorly from the olfactory region of the 

 cerebrum an afferent tract: Tradus olfacMiahenvIaris. To this is 

 associated in those vertebrates above the amphibia a bundle from cerebral 



