The following facts were observed during a visit to Anglesea and Carnarvonshire in company with Prof. Hughes in the early part of July. They still further bear out and confirm the evidence given in a short communication to the Geological Magazine for May, 1881, bearing upon the position of the Twt Hill conglomerate. Among the arguments brought forward against the Cambrian age of that conglomerate, much stress has been laid upon the absence fromit of felsite pebbles, which are so characteristic of the Cambrian conglomerate in the neighbourhood of Bangor.