In my former note I adduced the reasons which make me confident that the conglomerates of the south of the Isle of Man, which have been hitherto classed as Devonian, are not Devonian, but are later than the Carboniferous Period. I will now turn to the problem of what they really are. It is a well-known fact that in the Isle of Man the Secondary and Tertiary rocks are wholly absent. This is the view of all those who have examined the island, and is in fact perfectly palpable. The series of older rocks terminates with the upper layers of the Carboniferous Limestone; above this there are nothing but deposits of Quaternary Age. The red conglomerate to which I have referred contains no trace of any Secondary or Tertiary fossils, nor is there the smallest ground for believing that it belongs to either of those series. Does it then belong to the Quaternary beds? This conclusion is inevitable, and, as we shall see, is an exceedingly interesting one.