580 C. CALLAWAY ON THE ARCHZAN AND 
specimens which widely differ from Dalman’s type, and closely 
approximate to the Angleseyform. It would be hazardous to found 
important conclusions upon slight differences in the case of such a 
plastic species as O. calligramma. 
Neseuretus ramseyensis, a fragment, has also been referred to 
this horizon* ; but its occurrence can at present decide nothing; for 
it is also said + to have been found by Professor Henslow at Treior- 
werth, in association with Asaphus Powisii and other Bala fossils. 
The Trilobitic fauna of Bryn-gwallen is not sufficiently distinct to 
enable us to fix an exact horizon. The evidence seems to point toa 
Llandeilo age. At least it is clear that it would be hazardous to 
place the Trilobite beds lower than Arenig. 
I by no means contend that these rocks are not Cambrian. I 
simply maintain that the evidence adduced strengthens the position 
of those who doubt. 
The rocks of Llanbabo may have some bearing upon the question, 
though perhaps not a decisive one. In a small quarry at the church, 
I found in black shales a Diplograptus, probably D. foliaceus. These 
shales, in a large quarry in the next field, pass down through thin- 
bedded sandstone into massive grit. This series seems to be the 
same as that which overlies the granitoid mass at Pen-lon, and the 
strike also coincides. There is, therefore, at least a probability that 
this grit is nearly at the base of the Paleozoic succession in Anglesey, 
and the Diplograptus-shale is not 50 feet above the grit. Half a 
mile te the south this Graptolite is found in association with other 
well-marked forms, so that the horizon can be fixed. These fossils 
have been determined for me by Prof. Lapworth as follows:— 
Dicranograptus ramosus, Hall. 
Climacograptus Sharenbergti, Lapw. 
Dicellograptus Morrisii, Hopk. 
Leptograptus, sp. 
This fauna, in Prof. Lapworth’s opinion, indicates a Bala age. If 
the underlying grit is the equivalent of the Orthis-grit, the Ordovician 
age of the latter is demonstrated. 
Elsewhere in Anglesey, Prof. Hughes found a Graptolite fauna 
which Prof. Lapworth refers to the “highest Arenig or lowest 
Llandeilo ”i. 
in the present state of our knowledge, I am obliged to admit that 
the presence of Cambrian rocks in Anglesey has not been proved. 
This concession may seem to justify the contention that the altered 
groups may have furnished pebbles to the basement conglomerates, 
and yet be no older than Lower Cambrian. To this I would 
reply :— 
1. The Pre-Palzozoic rocks of Anglesey are utterly unlike the 
admitted Lower Cambrian of Harlech and Llanberis. To say 
nothing of the metamorphic schists and gneiss, we may ask — Where 
* Hughes, Quart. Journ. Geol. Soc. vol. xxxvi. p. 238. 
+t Ramsay, Geol. N. Wales, 2nd ed. pp. 225, 226. 
¢ Hughes, zdzd. 
