90 Reports and Proceedings— 
3. “On the Jersey Brick Clay.” By Dr. Andrew Dunlop, F.G.S. 
This clay is of a dull yellow colour and somewhat sandy; in 
places it effervesces with acids; bedding and lamination have been 
noted. The lower part contains angular stones, usually with their 
longest diameter parallel to the surface of the underlying rock, and 
either derived from it or trom some other rock not far distant. The 
bulk of the rocks consist of granite, diorite, rhyolite, quartz-felsite, 
etc., but there is an argillaceous shale, locally hardened, which is 
largely developed over considerable areas. The clay occurs in 
patches, covering all kinds of rocks, and is spread over the raised 
beaches ; it seems more abundant on the higher grounds. A similar 
clay occurs in Normandy and in the other Channel Islands. 
The author was disposed to regard this clay as probably a fluviatile 
deposit laid down towards the close of the Glacial Period, when 
the Channel Islands were at a lower level and united to the main- 
land. Subsequently he conceived that it might be the result of the 
decomposition of shale, felspathic porphyry, etc., some sections 
seeming to show this process as still going on; the clay, too, seems 
better developed over this class of rock ; if so, it would require a 
moving force more energetic than ordinary rainwash. 
II.— Jan. 9, 1889.—H. Woodward, LL.D., F.R.S., Vice-President, 
in the Chair.—The following communications were read :— 
1. “On the Growth of Crystals in Igneous Rocks after their 
Consolidation.” By Prof. J. W. Judd, F.R.S., F.G.S8. 
That the characteristic structures of the “ granophyric” rock were 
not acquired by them during the act of consolidation, but have 
resulted from secondary changes taking place subsequently, was 
suggested in a former communication to the Society. Additional 
evidence was now brought forward concerning the nature of the 
processes by which these structures — variously known as the 
micropegmatitic, the centric or ocellar, the pseudospherulitic, the 
microgranitic, and the drusy or miarolitic—which are found in the 
peripberal zones and the apophyses of granitic intrusions, must 
have been produced. 
That fragments of crystals in detrital rocks undergo enlargement 
and redevelopment has been shown by Sorby, Van Hise, Bonney, 
and many other authors. The fact has also been frequently recog- 
nized that curious outgrowths may often be detected in connection 
with the crystals of igneous rocks; such outgrowths have usually 
been regarded, however, as having been formed during the original 
consolidation of the rock. 
In a ‘“ labradorite-andesite” (labradorite of French petrographers) 
belonging to the older or ‘felstone” series of ejections in the Ter- 
tiary voleano of Mull, large crystals of a plagioclase-felspar, near to 
labradorite in composition, are found to exhibit large and remark- 
able outgrowths of very irregular forms. The distinction between 
these outgrowths and the original crystals is rendered very obvious 
from the circumstance that the original crystals have been corroded 
by the enveloping magma and contain enclosures of the same, and 
