TABLE VI. 



Syitematio Surrey of the principal organs of the ideal Primitive Vertebrate, 

 the hypothetical parent-form of Vertebrates, and of their development 

 from the germ-layers. 



Primary Germ- 

 layers. 



Secondary Germ- 

 layers. 



Most important Organs of 

 the Primitive Vertebrato, 



L 

 Skin-layer 



(Animal germ-layer, / 



Baer). 

 Lamina dermalis, H. 



Exoderma. 



\ 



Skin-sensory layer 



(Skin-stratum, Baer), 

 or 



Sen?ory layer. 

 Lamina neurodermali$ t 3 



n. 



Skin -fibrous layer 



(Flesh-stratum, Baer), 



or 



Flesh -layer. 

 Lamina inodermalU, E. 



4. 

 S. 

 6. 



r. 



Outer skin (Epidermis). A 

 simple cell-covering of the 

 outer surface. 



Spinal tube (Tubu$ nedul~ 

 laris) (with the organs of 

 sense : the nose, eyes, organs 

 of hearing). 



Primitive Kidneys (Protone- 

 phra) (a pair of simple ducts, 

 primitive kidney ducts). 



True skin (Corium) (CWi* and 

 subcutis). 



Muscles of the trunk (dorsal 

 and ventral muscles). 



Note-chord {Chorda dorsalis). 



Exoccelar, or Parietal Ccelom- 

 epitbelium ("the inner cell- 

 covering of trie body-wallX 

 tes% 



8. Male sexual glands (Teste 



Coeloma, or Body-cavity. A space between the body-wall and the 

 intestinal wall, between the exoderm and the entoderm, filled with lymph 

 (colourless blood). 



n. 



Intestinal laver 

 (Vegetative germ 



layer, Baer). 

 Lamina gastralis 



Entoderm* 



L 



in. 



Intestinal-fibrous layer 



(Vascular stratum, Baer), 



or 



Vascular laver. 

 Lamina inogastralit, H. 



IV. 



Intestinal-glandular layer 



(Mucous stratum, Baer), 



or 



Mucous layer. 

 lamina mycogattrali*, M. 



I. Female sexual glands (Ovary). 



). Endoccelar, or Visceral Cos- 

 lom-epithelium (the outer 

 cell-covering of the Intestinal 

 tube.) 

 11. Principal blood-vessels (primi- 

 tive artery or dorsal vessel, 

 and the primitive vein or 

 ventral vessel). 



I. Mesentery. 



>. Muscular intestine wall (fi- 

 brous intestinal wall). 



14. Intestinal epithelium (innel 



cell-covering of the intestinar 

 tube). 



15. Intestinal glandular epithe- 



lium (liver-cells and other 

 Intestinal glandular cells\ 



