546 C. JUDSON HERRICK 



EXPLANATION OF FIGURES 



80. Section no. 29, through the caudal border of the chiasma ridge. The dorso- 

 median ridge and the pais doisalis thalami cannot be clearly separated at this 

 level. 



81. Section no. 41, thiough the middle of the habenulae. 



82. View of the inner surface of the brain of a human embryo of 6.9 mm. Drawn 

 fiom the wax model by Ziegler of the embryo Br 3 of the His series and lettered 

 after His, '04, p. 56, fig. 34. The region marked C.s. includes not only the corpus 

 striatum but also the preoptic nucleus and other parts of the lhinencephalon. 



(1) Mai go reuniens (rhinencephalon with rhinencephalon and pallium). 



(2) Margo thalamicus (pallium with thalamus, site of the di-telencephalic fissui e) . 



(3) Margo peduncularis (corpus striatum with thalamus, site of the sulcus dien- 

 cephalicus medius). 



(4) Margo hypothalamics (coipus stiiatum with hypothalamus). 



83. Diagrammatic cross section through the diencephalon of Urodela and Anara. 

 On account of the diencephalic flexure, the section must be taken obliquely to the 

 long axis of the brain in the plane A-B of fig. 22, in order to pass transverse to the 

 thalamic axis. The numbers 1, 2, 3 and 4 and the letters A, B and C mark cor- 

 responding structures in figs. 83 and 84, the two figures being designed to illus- 

 trate the way in which the cerebral hemispheres have been formed by the lateral 

 evagination of the walls of the neural tube ; see the text. p. 477. 



A, sulcus diencephalicus dorsalis. 



B, sulcus diencephalicus medius. 



C, sulcus diencephalicus ventralis. 



D, roof plate . 

 V, floor plate. 



84. Diagrammatic cross section through the cerebral hemispheres in front of the 

 lamina terminalis of the frog. 



A, dorsal angle of hemisphere. 



B, zona limitans lateralis and fissui a endo-rhinalis. 



C, ventral angle of hemispheie. 



D-V, zona limitans medialis and fissure limitans hippocampi. 

 L.F.T., lateral forebrain tract. 

 M.F.T., Medial forebrain tract. 



