160 BRITISH PALAOZOIC SPONGES. 
when mounted in Canada balsam, are translucent, and in some instances quite trans- 
parent. They are all siliceous, and the silica is either chalcedonic or crystalline. 
As arule the axial canals are abnormally enlarged; in some cases the wall of the 
spicule is reduced to a thin crust inclosing the canal, and even this is occasionally 
destroyed, and merely the solid infilling of the canal remains. The anchoring-rods 
have precisely the same appearance, and are in the same state of preservation as the 
skeletal-spicules. The anchoring-spicules occurring in the Yoredale rocks at 
Richmond, Yorkshire, have a translucent, horny aspect ; they consist of chalcedonic 
silica. 
This species is very abundant and widely distributed in the Lower Carboniferous 
of Scotland, and in the cherts and limestones of the Yoredale series of Yorkshire. 
In some places beds of rock, six inches (‘015 m.) in thickness, are made up of bands 
of the anchoring-spicules crossing over each other in a generally horizontal direction, 
and it is probable that many of the Sponge-beds, mentioned in the Introduction, 
principally consist of the detached spicules of this species. As already mentioned, 
some of the anchoring-spicules are met with in the Ordovician strata of Girvan, 
Ayrshire. This species may be distinguished from Hyalostelia parallela, M‘Coy 
sp., by the much more robust character of the spicular rods. 
Distribution.—Carboniferous, Yoredale series: Yorkshire,—Richmond, Arken- 
dale, near Muker; Gunnerside Gill, Swinner Gill, Sargill Beck, and throughout 
Swaledale generally, where the main chert crops out. | Flintshire,—Halkin, Henblas, 
near Holywell. 
Scornanp.—Upper part of Lower Limestone series : Cunningham Baidland, Low 
Baidland, Auchenskeith, Thirdpart, Hourat, Law, Birkhead, Blackstone, Dalry. 
Upper Limestone series: Linn Spout, Glencart, Lambridden, Dalry, Ayrshire ; 
Gateside, Beith ; Brockley, Lesmahagow ; Ponniel Water, Douglas. Messrs Young 
cite also the following localities: Dockra, Hillhead and Trearne quarries, near 
Beith ; Waterland Quarry, Dunlop, Ayrshire ; Corrieburn, Campsie Hills, Bathgate, 
Chapel Quarry, near Kirkaldy, Fifeshire. Mr. R. Etheridge, junr., also records 
this species from Petershill and Galabraes quarries, near Bathgate; Tartraven old 
quarry, near Linlithgow; Charlestown Quarry, near Inverkeithing; Roscobie 
Quarry, near Dunfermline; Laddedie Quarry, near Cupar; Airfield, near Cousland, 
by Dalkeith. 
Iretanp.—Calp series: Bundoran, Co. Leitrim, Tyrone. Upper Limestone 
series: Ben Bulben, near Sligo. 
