_ Vol. 58. ] JASPERS OF SOUTH-EASTERN ANGLESEY. 439 
occur in Anglesey at Cerrig Ceinwen and elsewhere, and showed 
appearances which might be taken for the relics of obliterated 
organisms. In these cases they were not associated with igneous 
rocks, but with limestones and umber; and these associates 
occurred in every district among the Monian schists, which were 
overlain at no great distance by basal Cambro-Silurian con- 
glomerates and shales.in an unmetamorphosed condition, and 
without a sign of any such materials as limestone, umber, or 
jasper. There could be no doubt as to their age. 
The ‘jaspers’ described by the Author seemed to be of more than 
one kind. There was not, so far as the speaker could learn, any- 
thing to connect them with radiolaria or with the Arenig rocks. 
Prof. Sortas observed that cherts should not be accepted as 
radiolarian, unless they contained undoubted remains of radiolaria. 
He was far from inferring a necessary connection between radio- 
larian ooze and deep-sea deposits, but here we were asked to 
believe that such ooze occurred in the heart of igneous rocks. The 
necessary relationship between this occurrence and the pillowy 
structure of the diabase required to be proved. The slide which 
was said to represent radiolarian chert seemed to him very like 
ordinary spherulitic rhyolite. He congratulated the Author on the 
admirable, painstaking work which he had accomplished. 
Mr. CoomAraswAmy said that radiolarian remains did not 
necessarily imply a deep-sea origin for the formation in which 
they occurred. He had recently found radiolarian remains in the 
porcellanous plant-bearing shales of Upper Gondwina age, which 
occurred at Sripermatur, near Madras. 
Dr. Frerr stated that, in the supposed Arenig rocks on the 
southern border of the Scottish Highlands, many of the difficulties 
with which the Author had met in Anglesey were repeated. While 
in certain sections it was clear that there was a break between 
the supposed Arenigs and the Highland Schists to the north of them, 
in others there seemed to be no evidence of any interruption. 
At Aberfoyle some of the Highland rocks were as little meta- 
morphosed as any of the supposed Arenigs. 
The Prestpenr agreed with the previous speakers in their 
appreciation of the value of the detailed geological work which the 
Author was doing in Anglesey, and welcomed this fresh instalment 
of the publication of his results. It was only by detailed work like 
this, that problems of such complexity as those presented by 
Anglesey would ever besolved. It was indeed most interesting to find 
here another example of that peculiar association of certain character- 
istic sediments and igneous rocks which had already been described 
from Southern Cornwall, Southern Scotland, and the Southern 
Highlands and elsewhere; and the same apparent geographical, 
lithological, and structural gradation from unaltered, through altered, 
into acknowledged metamorphic rocks. He had himself held the 
opinion that this peculiar association and gradation would ultimately 
be found to be due partly to the physical conditions of such 
an area at the time when its later recognizable sediments were 
2H 2 
