84 HH. B. Muff & R. G. Carruthers—Arenig Rocks, W. Ireland. 
ft. in. 
10. Limestone, grey, oolitic, with a Mat uneven top: 
4 to 8 inches ... ce On One 
11. Limestone, rubbly, slightly “eases: 9 to 5 madhe a EES 
Upper Trigonia- 12. Ragstone, hard, grey, shelly; Trigonia costata 
Grit. (common in the upper portion), Acanthothyris 
spinosa, Ter. globata, Pterra digitata, Nerinea sp. 
The top-surface is covered with oysters, and bored 
in places by Lithophagi: seen BEE ns ing baz) 
It was from rubble of the Anabacia-Limestone equivalent, I ee 
that the Prosopon was obtained at Tor Hill. 
Concerning the Winner-Hill section, it may be remarked that there is 
no clear representative of the Dundry Freestone or of the Upper Coral- 
Bed. The oyster-covered and bored top-portion of the Upper- Friganic 
Grit hints at a non-sequence. 
VII.—Note on tHe Occurrence or ArentG Rocks IN THE WEST OF 
IRELAND. 
By H. B. Morr, B.A., F.G.S., and R. G. CarruruErs. 
HILST examining the tract of Lower Paleozoic rocks and 
metamorphic schists around Killary Harbour, in Connemara 
(an examination primarily undertaken to ascertain the relations of the 
fossiliferous sediments to the schists in that area), an extensive tract 
of Arenig rocks has been discovered on both sides of the harbour. 
In 1905 Didymograpti of the extensus and superstes types were found, 
and during last Summer ‘several specimens of Phyllograptus and 
Tetragraptus also, together with many other forms. 
Professor Lapworth and Miss Wood (Mrs. Shakespear), who kindly 
examined some of the best preserved specimens, are of opinion that 
certain of the graptolites resemble American forms, and may include 
genera and species new to Britain, though they do not wish to give 
a definite opinion until more specimens have been obtained. From 
the evidence already before us it would appear that either a great 
reversed fault or upturned thrust plane must separate the Arenig rocks 
on the north from Ludlow beds on the south. The members of both 
groups dip to the north, the Ludlow rocks passing beneath the Arenig 
strata. It may be added that an abundance of rock-sections and an 
apparent absence of acute folding give every hope that the structural 
relations of the rocks and the distribution of this peculiar fauna may 
be fully elucidated in the near future, 
On the maps of the Geological Survey published in 1874 the 
lowest fossiliferous Silurian rocks (Doolough Beds) are lettered 6°, and 
are referred somewhat doubtfully to the Lower Llandeilo in the 
Memoir on Sheets 83 and 84. During the revision of the district in 
1896 black shales with Lower Llandeilo fossils were proved in several 
localities, and it was suggested that ‘‘ perhaps even Arenig graptolites ”’ 
might be present.’ 
1 Annual Report of Geol. Surv. for 1896, p. 49. 
