296 



NERVOUS SYSTEM OF VERTEBRATES. 



of the lateral lobes, to the whole extent of which they are distrib- 

 uted. These are the olfactory lobes, including the equivalent of 

 the nucleus thaeniae of higher forms. The vertical groove in the 



Fig. 146. — An oblique section through the inferior lobes and forebrain of Lam- 

 petra. Ill, median ventricle; a.o., olfactory lobe; </./>., postoptic decussation; e, epi- 

 striatum; ep., epiphysis; tr.e-s., neurites of epistriatum cells to striatum; tr. l-b., 

 tractus lobo-bulbaris; tr.o., tractus opticus; tr.o-h., tractus olfacto-habenularis; 

 tr.s-th., tractus strio-thalamicus ; tr.th-sac, tractus thalamo-saccus; sac, saccus 

 vasculosus. 



lateral wall separating the olfactory lobes from the bulbs is the 

 only external indication of the olfactory tract, which is usually 

 recognizable externally in other vertebrates. A part of the olfac- 



