The representation of the groups as here given in the diagram on a flat surface, is much too simple.
The branches ought to have diverged in all directions.
If the names of the groups had been simply written down in a linear series the representation would have been still less natural; and it is notoriously not possible to represent in a series, on a flat surface, the affinities which we discover in nature among the beings of the same group.
Thus, the natural system is genealogical in its arrangement, like a pedigree.