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TEXT-BOOK OF EMBRYOLOGY. 



ORNITHORHYNCHUS 



FIG. 408. A-F (Edinger) are sagittal sections showing structures lying in the median line and also 

 paired structures (e.g., pallium) lying to one side of the median line. The cerebellum is 

 black. It is doubtful whether the membranous roof in A indicated as pallium is strictly 

 homologous with that structure in other forms In B, Pallium indicates prepallial structures. 



Aq. Syl., Aquseductus Sylvii; Basis mesen., basis mesencephali; Bulb, olf., bulbus olfactorius; Corp. 

 striat., corpus striatum; Epiph., epiphysis; G. h., ganglion habenulae; Hyp., hypophysis; 

 Infund., infundibulum; Lam. t., lamina terminalis; Lob. elect., lobus electricus; L. vagi, 

 lob us vagi; L. opt., mid-brain roof; Med. obi., medulla oblongata; Opt., optic nerve; Pl.chor., 

 plexus chorioideus; Rec. inf., recessus infundibuli; Rec. mam., recessus mammillaris; Saccus 

 vase., saccus vasculosus; Sp. c., spinal cord; ventr., ventricle; v. m. a., velum medullare 

 anterius; v.m.p., velum medullare posterius. 



G and H show the mesial surface of the cerebral hemispheres in a low (G) and high (H) Mammal. 

 G. Elliot Smith, Edinger, slightly modified. 



The exposed gray matter of the olfactory regions is shaded, the darker shade indicating the archi- 

 pallium (preterminal area and hippocampal formation), the lighter shade indicating the 

 rhinencephalon. which consists of the anterior and the posterior (principally pyriform) olfactory 



