TABLE VI. 



Systematic Survey 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 Vertebrate. 



L 



Skin-layer 



(Animal germ-layer, 



Baer). 

 Lamina dermal is, H. 



Exoderma. 



Skin-sensory layer 



(Skin-stratum, Baer), 



or 



Sensory layer. 



Lamina neurodermalis, H. 



Skin-fibrous layer 



(Flesh-stratum, Baer), 



or 



Flesh-layer. 



Lamina inodermalis, H. 



1. Onter skin (Epidermis}. A 

 simple cell-covering of the 

 onter surface. 



8. Spinal tube (Tubus medul- 

 laris) (with the organs of 

 sense : the nose, eyes, organs 

 of hearing). 



3. Primitive Kidneys (Protone- 



phra) (a pair of simple ducts, 

 primitive kidney ducts). 



4. True skin (Corium) (Cutis and 



subcutis). 



5. Muscles of the trunk (dorsal 



and ventral muscles). 



6. Notochord (Chorda dorsalis). 

 1. Exoccelar, or Parietal Ccelom- 



epithelium (the inner cell- 

 covering of the body-wall). 

 8. Male sexual glands (Testes'), 



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). 



Intestinal laver 

 (, Vegetative germ- 

 layer, Baer). 

 Lamina gastralis, H. 



Entodeima. 



in. 



Intestinal-fibrous layer 



(Vascular stratum, Baer), 



or 



Vascular laver. 



lamina inogastralis, H. 



IV. 



Intestinal-glandular layer 



(Mucous stratum, Baer), 



or 



Mucous layer. 

 Lamina mycogastralis, B. 



Female sexual glands (Ovary). 



Endocoelar, or Visceral Coe- 

 lom-epithelium (the outer 

 cell-covering of the intestinal 

 tube.) 



Principal blood-vessels (primi- 

 tive artery or dorsal vessel, 

 and the primitive vein or 

 ventral vessel). 



Mesentery. 



Muscular intestine wall (fi- 

 brous intestinal wall). 



Intestinal epithelium (innel 

 cell-covering of the intestinar 

 tube). 



Intestinal glandular epithe- 

 lium (liver-cells and other 

 intestinal glandular cells); 



