Note 19 — LESSON XXI.

Animals and plants are divided into Classes, Orders, and Families, that we may arrange and study them more readily. A Class contains many objects with some great points of resemblance—as the Class of Insects. The Orders bring those together which have yet more points of resemblance—as the Order of the Same-Wings. Families contain those yet more closely related—as the Aphis Family, the Frog-hopper Family. The Classes, Orders, and Families have Latin or Greek names, of which in this book we give only the meaning.