I am examining a new classification of invertebrate animals, and have a small vial of alcohol containing 30 specimens of a small, pale animal -- probably teneral specimens of some species of insect. It seems that my intention is to test the accuracy and usability of the key by using it to identify my insect. According to this classification there are, all told, 650,000 species of invertebrates, all insects except for 25,000; and of this latter number the great majority are species of Crustacea, with a few of Myripoda.