96 Scientific Proceedings, Royal Dublin Society. 
inserted on the l-inch map. This is only one instance out of many 
of the rather careless way in which the reductions from the 6-inch 
map have been effected. 
It is probable that this is not the only locality in Leinster 
where variolites are to be found. Thus, DuNoyer' speaks of green- 
stone near Enniscorthy as weathering “into small rough pimples,” 
and Jukes sagaciously remarks that ‘this would probably be the 
variolite of Continental authors.”’ On the coast of Waterford, also 
in Bonmahon Bay, diabase ‘‘mandelstein” occurs in association 
with rocks which I have reason to believe are variolitic. 
The greenstone which lies on the right-hand side of the road 
going from Roundwood, not far from the church of Raheen, is a 
holocrystalline ophitie diabase, having a specific gravity of from 
2°78 to 3:0. The lower value is exceptional; the mean is 2°97. It 
is of medium grain, the crystals of plagioclase, felspar, and 
pyroxene, which are its chief constituents, frequently attaining a 
length of 7 mm. as seen in thin slices. Plates of altered ilmenite, 
which are not uncommon, sometimes measure as much as 3 mm. 
Across. : 
The felspar affects long, more or less rectangular outlines, is 
frequently twinned on the albite—sometimes on the Carlsbad plan, 
and extinguishes at large angles pointing to labradorite and 
bytownite. The pyroxene occurs in colourless sections with well- 
‘developed cleavage; it extinguishes at from 82° to 45°, and is 
frequently rendered ophitic by included felspar. Of olivine there 
is no certain trace, but it is by no means impossible that it was 
originally present. If in its fresh state the rock was an ophitic 
dolerite, it has since its extension suffered so much mineral change 
that its pristine character can only be recognized with difficulty. 
It has yielded both to the weather and to earth pressure, but of 
pressure the effect has been small compared to that of the 
weather. Thus, as shown in fig. 1, the augite has been nearly all 
converted into chlorite, which has eaten into it along numerous 
irregular cracks, and extending from them has produced a ground- 
work of chlorite, in which only small isolated fragments of the 
original mineral remain. These, which still preserve a common ° 
‘ Memoirs of the Geological Survey, 167, 168, 178, and 179, p. 13 (1865). 
