376 Reports and Proceedings — Geological Society. 
developed, and gives tke name of elvanites to tliose granitic rocks in 
wbicb part of tke constituents are not perfectly crystallized. Tbe 
elvanites pass into true granites on tbe one band, and on tbe other 
into plutonic or volcanic rocks. Tbey are tbus “ passage-rocks ” 
between tbe two seetions. 
Tbe autbor apparently regards all granites as formed by tbe 
metamorpliosis eitber of tbe sedimentary rocks in wbicb tbey occur, 
or of tbe plutonic rocks associated witb tliese. Even intrusive 
granites are tbe product of an extreme degree of metamorpbosis. Of 
metamorpbosis be distinguisbes two kinds, namely : — Metapepsis, or 
regional metamorpbosis, extending over larger or smaller areas, and 
due to aqueo-igneous action ; and Paroptesis, or local metamorpbosis, 
eaused by beat generated at or near local igneous action or a pro- 
trusion or slieet of igneous rock. 
Tbe autbor tben indicates the application of tbese principles to 
tbe Classification of tbe granitic rocks of Ireland in tbe ckrono- 
logical Order of tbe sedimentary deposits witb wbicb tbey are asso- 
ciated, and divides tbese rocks into eleven classes, corresponding to 
tbe Cambrian, Cambro-Silurian, Silurian, Carboniferous, Triassic, 
and Tertiary series, witb five intermediate classes, tbe latter generali}' 
divided again into sub-classes. Tbe granitic rocks of different 
districts in Ireland are tben described in some detail, and referred 
to tbeir places in tbe proposed cbronological scheine. 
16. “ The Cambrian Eocks of Soutk-East Ireland.” By G. H. 
Kinahan, Esq., M.E.I.A. Communicated by Prof. Eamsay, F.E.S., 
F.G.S. 
Tbe autbor states tbat tbese rocks are greatly altered by rneta- 
morphic action. Quartz rock occurs in dykes and other masses 
among tbe Cambrian and Cambro-Silurian rocks, but chiefly among 
tbe former ; it may be foliated and converted into quartzite by wbat 
tbe author calls metapepsis (see preceding paper). 
Of tbe Cambro-Silurian rocks tbe base is seen only in two places, 
at Greenore and on the S.W. coast of Wexford. At tbe former it is 
a fine reddisk conglomerate, lying on or against sckists; at tbe latter 
a massive slate conglomerate. Tbe rocks of tbis series in ascending 
order are : — 1. Black carbonaceous sbales and slates, or grey beds 
witb subordinate beds of grit ; 2. Green and grey grits, sbales and 
slates ; 3. Tbe Ballymoney series of green, grey, black, and red 
grits, sandstones, slates and sbales, witli interstratified igneous rocks; 
4. Eed, purple, and green beds, usually more or less argillaceous. 
The Cambrian formation generally consists of green, purple, or 
reddish grits, shales and slates, but here and there witb grey or 
even black beds. Tbe autbor describes tbe Cambrian rocks in tbe 
various areas in whick tbey occur, namely, at 
Howtk, where tbey are but little altered in tbe N., becoming more 
altered towards tbe S. 
Bray Head, generally unaltered, and containing many specimens 
of Oldhamia, and witb massive dykes of quartz rock. 
S.E. Wicklow, where tbe Western boundary is doubtful. Near 
Carrick mountain and to tbe westward tbe rocks are mucb altered, 
