Securifera, [503]Segmentation, [149], [237];of ovum of Smicra, [545]Segments, [88], [90];number of, [87]Selys, De, on dragon-flies, [425], [427]Semi-pupa, [497]Sense organs, [121]-[123]Senses, [541], [544], [553]Sericostomatides, [474], [482]