THE INTEEBKAIN OR THALAMENCEPHALON. 



137 



tudinal lundh (Fig. 44): an elongated, perpendicularly placed nucleus 

 which lies near the median line, one on each side. From it develop the most 

 anterior fibers of the Fasciculus longitudinalis posterior, the bundle which 

 we have repeatedly met from the spinal cord on to the interbrain. That it 

 later receives bundles from the nuclei of the cerebral nerves has already been 

 mentioned. 



The nucleus of the posterior longitudinal fasciculus lies rather far 

 ventral, and might, in fact, be reckoned with the hypothalamus instead of 

 the metathalamus. In fishes it certainly belongs to the former. 



Lateral from it — i.e., in the postero-lateral portion of the thalamus — 

 lies the nucleus ruber tegmenti: a usually well-defined nuclear mass from 

 which fibers arise which decussate soon after their origin, pass dorsally, and 



Pig. 85. — Frontal sections through the boundary between the base of the 

 midbrain and lobi inferiores. From the teleost: Zoarces mviparus. (A young 

 specimen three centimeters long.) a, Nucleus rotundua thalami. 6, Supplemen- 

 tary nuclei of the same, c, Post, ganglion of inferior lobe, e, Infundibulum. f, 

 Tr. lobo-eerebellaris frontalis, g, Tr. lobo-cerebellaris caudalis. h, Fritsch's com- 

 missure, i, Ggl. profundum mesencephalici lat. Ic, Ggl. lat. mesencephalici Torus 

 semie. I, Valvula eerebelli. m, m', n, Single portions of the fiber-bundles from the 

 roof (see also Fig. 67). o, Nucl. N. Oeulomot. and Fasciculus longitudinalis 

 post, p, Commissura post. 



end in the cerebellum. These bundles are comprehended under the term 

 Tractus tegmento-cerebellaris: the anterior peduncle of the cerebellum. For 

 the nucleus see Fig. 83; for the tract see Figs. 71 and 84, and for the 

 decussation see Figs. 65, 83, and 84. 



We turn our attention^ now to the structure at the base of the inter- 



* Seven pages of the original (131 to 137) are here briefly summarized. 



