Five distinct varieties of black coal, of well-characterized.
In some instances these differences are so marked that they have led some botanists to regard as distinct species many forms usually esteemed by others as varieties only.
There are several varieties of snakes, of which three species (all vipers) are poisonous.
In the upper valleys of the Alps there are many local varieties, one of which at Ossola is like the Scottish blacklace.
In the secondary tissues of Dicotyledons we may have, as already described, considerably more differentiation of the cells, all the varieties being referable, however, on the one hand to the tracheal or sieve-tube type, on the other to the parenchyma type.