Keywords: Origin of Vertebrates Fig 061.png Fig 61 ”A Entosternite of Limulus; B Entosternite of Thelyphonus Ph position of pharynx 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 Thelyphonus Arachnida anatomy |