164 REPORTS ON THE STATE OF SCIENCE. 
I. Arenig Beds. 
(4) Coarse grit . ‘ : ; , : é . 150 feet. 
(3) Fine grit and tuff associated with black chert, 
graptolitic shale, and a prominent band of 
breccia 30 feet thick . E : - : . Thickness doubtful. 
(2) Coarse grit. : : : : : . 110 feet. 
(1) Coarse conglomerate. ; ; 5 : . About 600 feet seen. 
The black shales have yielded the following considerable series 
of graptolites, which have been kindly determined hy Miss G. I. 
Elles, D.Sc., and indicate the zone of Didymograptus extensus. The 
associated cherts contain radiolaria :— 
GRAPTOLITES FROM THE ARENIG BEDS OF GLENSAUL. 
Dictyonema, sp. Thamnograptus, sp. 
a Dendrograptid. Didymograptus eatensus, Hall (common). 
Tetragraptus pendens, Elles, D. filiformis, Tullberg. 
T. Amii, Lapworth M.S. D. fasciculatus, Nich. 
T. quadribrachiatus, Hall. D. bifidus, Hall. 
Clonograptus Lapworthi, Rued. D. gracilis, Térnquist. 
In the Llandeilo rocks, both limestone and tuff, a large number of 
generally rather fragmentary fossils was found, which are being deter- 
mined by Mr. F. R. Cowper Reed. 
The crystalline igneous rocks, all of which we believe to be intrusive, 
are by no means so varied as in the Tourmakeady district, and are 
practically limited to one broad band of felsite, which is noteworthy 
from the fact that it almost everywhere contains pyroxene. 
The district is much faulted, large faults bound it on the EH. and 
W., a somewhat complicated system of faults approximately parallel 
to these bounding faults intersects it, and there are other dislocations 
of importance. 
Composition and Origin of the Crystalline Rocks of Anglesey.— 
Fourth Report of the Committee, consisting of Mr. A. 
Harker (Chairman), Mr. EK. GREENLY (Secretary), Dr. C. A. 
Matuey, and Professor K. J. P. Orton. 
Tue Committee record with great regret the loss they have sustained. 
in the death of Mr. J. Lomas, which occurred in the prosecution of 
geological research in Algeria. 
The work of the year has included the completion of the series of 
analyses of rocks of the hornfels type in Central Anglesey ; and now the 
pillowy diabase lavas with jaspers and other associated rocks (perhaps 
the most important in the island; of far-reaching importance, indeed, 
among ancient rocks beyond its limits) are being proceeded with. A 
series, also, of limestones and mudstones from the Carboniferous lime- 
stone and Old Red rocks have been analysed, which were collected 
during the survey of the Carboniferous limestone area in 1907 and upon 
which chemical information was greatly needed. Lastly, a gneissose 
marble, containing pseudomorphs after Forsterite, has been analysed. 
All the analyses are by Mr. John Owen Hughes, B.Sc., who con- 
tinues to devote to this work whatever time is allowed by his duties as 
Demonstrator in Chemistry in the University College of North Wales. 
