Head-s"ield, dor"al, of Ostreostraci, [327], [348]

Head-s"ield, dor"al, of Palæostracan, [348]

Head-s"ield, dor"al, of Pteraspis, [29]

Head-s"ield, dor"al, of Thyestes, [29], [31], [327], [332], [338], [340], [341], [348]

Head-s"ield, ventral, Scaphaspis, [349]

Heart, nerves, [2], [447]

Her"t, origin of vertebrate, [179], [451], [459]

Her"t, relative position in vertebrate and invertebrate, [175]

Her"t, veins forming vertebrate, [180]

Hemiaspis, [24], [25], [249], [250], [351], [414]