﻿218 Oanaclian Record of Science. 



YI. Pre-Cambrian in Wales. 



In the past suiumer I was enabled to spend a few days, 

 with the assistance of my friend, Mr. H. Tweeddale Atkin, 

 of Egerton Park, Kock Ferry, in examining the supposed 

 Pre-Cambrian rocks of Holyhead Island and Anglesey. 

 Fossils are very rare in these beds. As Sir A. Geikie has 

 shewn, the quartzite of Holyhead is in some places perfo- 

 rated with cylindrical worm-burrows; and in the micaceous 

 shales there are long, cylindrical cords which may be 

 algae of the genus Palcwchorda, and also bifurcating fossils 

 resembling Cho7idrites, but I saw no animal fossils. I 

 have so far been able to discover no organic structure in 

 the layers of limestone associated with apparently bedded 

 serpentine in the southern part of Holyhead Island. In 

 central Anglesey there are lenticular beds of limestone 

 and dolomite associated with Pre-Cambrian rocks, which 

 Dr. Calloway regards as probably equivalent to the 

 Pebidian of Hicks. In these there are obscure traces of 

 organic fragments ; and in one bed near Bodwrog Church, 

 I found a rounded, laminated body, which may be an 

 imperfectly preserved specimen of Cryptozoon or some 

 allied organism. The specimens collected have not, how- 

 ever, been yet thoroughly examined. These, and bther 

 pre-Cambrian deposits in Great Britain, correspond in 

 their testimony with the Eozoic rocks of North America, 

 as to the small number and rarity of fossil remains in the 

 formations below the base of the Pakeozoic, and the 

 consequent probability that in these formations we are 

 approaching to the beginning of life on our planet. Mr. 

 Edward Greenly, F.G.S.,' of Achnasheaw, Bangor, is now 

 engaged in a careful revision of the geological map of 

 Anglesey, and will give special attention to Pre-Cambrian 

 fossils. He has already discovered, in rocks supposed to 

 be of that age, organisms recognized by Dr. Hinde as 

 spicules of sponges.^ 



1 Journal Geological Society, Nov., 1896. 



