Keywords: Origin of Vertebrates Fig 150.png Fig 150 from Graber ”A Section of Subcostal Nervure of Hind Wing of Dytiscus to show patch of Poriferous Organs s o B Surface View of Poriferous Organs; the White Space round each Organ indicates the deeper lying Refringent Body which fills the bulging of the Canal seen in Transverse Section in C 1908 The Origin of Vertebrates https //archive org/details/originofvertebra1908gask Walter Holbrook Gaskell PD-old-auto-1923 1914 Origin of Vertebrates book Dytiscus anatomy |