286 Reports and Proceedings— 
species are described :—P. nidulata, and vars. major and minima, 
P. porifera, P. amphoralis, P. jugosa, P. bigibbosa, and P. galeata. 
This genus is, however, placed in the sub-order Cheilostomata, thus 
recognised for the first time in the Jurassic Series. 
Il.—April 26th, 1893.—W. H. Hudleston, Esq., M.A., F.R.S., 
President, in the Chair. The following communications were read :— 
1. “The Origin of the Crystalline Schists of the Malvern Hills.” 
By Charles Callaway, D.Sc., M.A., F.G.S. 
This paper was the third of a series of three. In the first of 
these, published in the Quarterly Journal in 1887, the author con- 
tended that many of the gneisses amd schists of Malvern were 
formed out of igneous rocks. In the second, which appeared in the 
Journal in 1889, he discussed the origin of secondary minerals at 
shear-zones in the Malvern rocks, and arrived at the conclusion that 
all the mica and much of the felspar, to say nothing of quartz and 
other minerals, were of secondary origin. In the present paper the 
author first pointed out that some of the most important mineral 
changes described in his second communication—such, for example, 
as the conversion of chlorite into biotite—had since been confirmed 
by independent investigators. He held that, as a whole, the gneisses 
and schists of Malvern had been formed by the crushing and shearing 
of consolidated igneous rocks; but he did not deny the possibility 
that here and there the foliated structure might have been produced 
in a fused mass. In the first stage of metamorphism the diorite or 
granite was crushed and decomposed. This slightly compressed 
rock could be traced step by step into a typical gneiss or schist. 
The signs of pressure progressively increased, and the mineral and 
chemical changes became proportionately greater. Reconstruction 
set in. The process of metamorphism did not always follow the 
same lines. Felspar was sometimes crushed into seams of fragments, 
and these, by partial re-fusion and pressure, were converted into 
eneissose lenticles of quartz and felspar. Intervening chlorite was 
changed to biotite, or even to muscovite or sericite. Thus a typical 
gneiss, consisting of quartz-felspar lenticles in a felt-work of mica, 
was formed out of a diorite. Sometimes the felspar was reconstituted 
without becoming fragmental, and it was then deposited on, or it 
included, idiomorphic mica; or a soda-lime felspar might, by a pro- 
cess of corrosion, be converted into quartz, or a soda-felspar, or both. 
In an early stage of metamorphism, the rock was often dirty and 
rotten through the abundance of chlorite and disseminated iron- 
oxide. The former being changed to mica, and the latter being 
either absorbed in the production of biotite, or reconstituted in a 
crystalline form, a sound clear gneiss was the result. In the com- 
pleted product, the signs of crushing and shearing were often 
entirely wanting. Even strain-shadows were rare in it. ‘The meta- 
morphism, however, was demonstrated in numerous localities by 
tracing the gradations inch by inch, and by the subsequent study of 
Jarge numbers of microscopic slides, in which the transition was 
still more clearly seen than in the field. 
