158 Scientific Intelligence. 
actually passed through the flooring leaving sharply cut outlines 
of their angles in the siliceous bricks. The refractory basic brick 
were made from an aluminous magnesian limestone. The result- 
ing fused mass was partly in semi-transparent crystals of long 
prismatic form, either colorless or greenish, with sp. gr. = 2°934; 
and they afforded on analysis the formula of a lime-and-magnesia 
pyroxene—the results obtained being Silica 55°35, lime 23°24, 
magnesia 16°20, alumina and iron-sesquioxide 4:20, water, loss, 
etc. 1:01 = 100, corresponding, if the alumina and iron are set 
aside as impurity, to ({Mg+4Ca)SiO.. : 
16. Fossil Sponge-spicules from a clay bed in the Carboniferous 
strata near Sligo, Scotland; by Professor H. J. Carrer (Ant. 
ag ist., V, xxxiii, 209).—Of the spicules here described, 
the most common is a sexradiate stellate kind, with 6 to 24 rays, 
according to the subdivisions of the arms, and having each ray 
spiriform—named by Carter Holasterella Wrightii ; the other 
kinds are the hexactinellid, lithistid, and a sausage-shaped ind, 
like that of some of the Reniere of the present day. Holasterella 
conferta has been found in a similar clay near Glasgow. Mr. Car- 
and, thirdly, that the rhomboidal excavations on the surface of 
the spicules and the partial absorption of the spicules themselves, 
leaving nothing but their moulds, arises from the changes which 
the siliceous element itself is now undergoing—that is, becoming 
decomposed and removed, or passing from an amorphous state 
into clear quartz prisms.” : 
17. Glaciation of the Shetland Isles and the Orkneys.— Ths 
subject has been well studied by Messrs. B. N. Peach and 4. 
orne. A paper by them on the Shetland Isles, published 10 the 
Quarterly Journal of the Geological Society for 1879, is referred 
to on page 72 of the last volume of this Journal; and another, 0” 
