I do not quite agree with your "grave objection to the whole process," which is "that if you multiply the anomalous species by 100, and divide the normal by the same, you will then reverse the names..." For, to take an example, Ornithorhynchus and Echidna would not be less aberrant if each had a dozen (I do not say 100, because we have no such cases in the animal kingdom) species instead of one.

What would really make these two genera less anomalous would be the creation of many genera and sub-families round and radiating from them on all sides.
Thus if Australia were destroyed, Didelphys in S.America would be wonderfully anomalous (this is your case with Proteaceae), whereas now there are so many genera and little sub-families of Marsupiata that the group cannot be called aberrant or anomalous.

Sagitta (and the earwig) is one of the most anomalous animals in the world, and not a bit the less because there are a dozen species.

Now, my point (which, I think is a slightly new point of view) is, if it is extinction which has made the genus anomalous, as a general rule the same causes of extinction would allow the existence of only a few species in such genera.

Whenever we meet (which will be on the 23rd [at the] Club) I shall much like to hear whether this strikes you as sound.