Geographical distribution has often been used, though perhaps not quite logically, in classification, more especially in very large groups of closely allied forms.
Temminck insists on the utility or even necessity of this practice in certain groups of birds; and it has been followed by several entomologists and botanists.
Finally, with respect to the comparative value of the various groups of species, such as orders, suborders, families, subfamilies, and genera, they seem to be, at least at present, almost arbitrary.
Several of the best botanists, such as Mr.
Bentham and others, have strongly insisted on their arbitrary value.