448 Proceedings of the Royal Irish Academy. 
localities, Derryloaghan, Co. Donegal (in prisms of a hair-brown 
colour), and also Bimbeg and Gweedore. 
During the past Easter vacation I was able to revisit the locality, 
and determine more accurately the conditions under which the mineral 
occurs. The townland of Calliagh (pronounced Kdll-yeh by the inha- 
bitants) lies nearly in the centre of a triangle of which Ballybay, 
Newbliss, and Monaghan are the summits, and may be reached by car 
from one or other of these points in about an hour's drive. The country 
presents a succession of hills, rather flatly conical than round, with 
patches of bog, bog-land, streams, or small lakes between them. It rises 
to an elevation of about 700 to 800 feet in the neighbourliood in question. 
The townland is sliown on the 6-inch map of the Ordnance Survey 
Sheet, I^'o. 13, of the Co. Monaghan ; and the point where the mineral 
occurs is marked thereon as " Quarries." (Its latitude and longitude 
are, K lat. 54° 11' 5", and W. long. 7° 1' 45".) Lying at a height of 
about 680 feet above the sea level, and forming part of a ridge which 
extends for several miles IT.IT.E. and S.S.W., it affords extensive 
views on nearly every side. About 1053 feet east of the quarry is the 
point known and marked as the " Giant's Grave," with an altitude of 
706 feet. The Quarry forms the summit of the hill known locally as 
Logwood Hill (as well as I could catch the pronunciation from my 
