28o NERVOUS SYSTEM OF VERTEBRATES. 



attached to the dorsal border of the corpus geniculatum laterale. 

 This shows clearly that the latter body forms the dorsal border 

 of the brain wall. The nucleus habenulae has risen up mesial 

 to it and pushed it outward. This will become clearer on compar- 

 ison with the relations of the visceral and somatic sensor}^ nuclei 



Fig. 142. — Transverse section of the habenular nuclei in the dog. From Cajal 

 (Textura, etc.). A, internal nucleus; B, external nucleus; C, stria thalami; D, 

 tractus habenulo-peduncularis. Only the internal nucleus corresponds to the 

 nucleus habenulae in the sturgeon (Fig. 140). 



in the medulla oblongata. In Figure 141 are drawn two sections 

 from the brain of a young freshwater dogfish {Amia), one through 

 the medulla oblongata and one through the nucleus habenulae. 

 It will be seen that in- both the somatic sensory centers, which 

 are morphologically dorsal, are turned out to the side and are 



