Keywords: Origin of Vertebrates Fig 148.png Fig 148 ”Section through the three Sense-Organs of Flabellum of Limulus bl blood-spaces; n nerve; gl layer of ganglion-cells; p pigment layer; ch 1 2 3 the three layers of chitin; ch t chitinous tubule in large tube of sense-organ; cap capitellum or swollen extremity of large tube; can very fine porous canals or canaliculi of chitin 1908 The Origin of Vertebrates https //archive org/details/originofvertebra1908gask Walter Holbrook Gaskell PD-old-auto-1923 1914 Origin of Vertebrates book Limulus polyphemus anatomy |