A very numerous and various class consisting of small animals, breathing through lateral spiracles, armed on all sides with a bony skin, or covered with hair; furnished with many feet, and moveable antennae (or horns), which project from the head, and are the probable instruments of sensation.
Despite this key, however, Linnaeus grouped insects together that shared other affinities. His genus Coccus, containing the scale insects, he placed among the 4-winged Hemiptera, along with aphids and other plant-attacking insects, even though females have no wings, and males have two wings.[2] Similarly, the sheep ked Hippobosca ovina (now Melophagus ovinus) was correctly placed among the Diptera, despite being wingless.[2]
^ abCarl von Linné, translated by William Turton (1806). Volume 1. A general system of nature: through the three grand kingdoms of animals, vegetables, and minerals, systematically divided into their several classes, orders, genera, species, and varieties. London: Lackington, Allen, and Co.