The fundamental form-elements may be reduced to the six proposed by Professor Penck as the basis of his double system of classification by form and origin.'
The form of the pear and of the apple respectively, although usually characteristic enough, is not by itself sufficient to distinguish them, for there are pears which cannot by form alone be distinguished from apples, and apples which cannot by superficial appearance be recognized from pears.
But the experience of all peoples in that memory requires to be helped by form.
The by-form Clodius, in its origin a mere orthographical variant, was regularly used for certain Claudii in late republican times, but otherwise the two forms were used indifferently.
