I cannot conclude this paper without remarking that none of the views therein are held dogmatically, and expressing the hope that former observers will renew their attention, and fresh ones take up the investigation of this complicated, yet interesting area. The difficulties are great, among which is the origin of the banded structure, in the rocks herein dealt with, which in my next paper I shall try to explain on the grounds of segregation, arising from, or taking place during the cooling of the common magma out of which all these rocks seem to me to have been formed.