278 Reports and Proceedings — Geological Society of London. 



and gives origin to the arms. On slicing two of the arms, no 

 plates were exposed which it was possible to certainly identify with 

 vertebral ossicles. Some hollow casts, from the Lower Ludlow of 

 Leintwardine, which have hitherto been regarded as too problematical 

 for determination, are shown to represent an organism closely allied 

 to Eucladia, and are provisionally referred to that genus. The 

 number of arms in this new species is less than in the original 

 (E. Johnsoni), and they are more nearly equal in size. A new genus, 

 closely allied to Eucladia, is founded on a small, well-preserved 

 specimen from the Wenlock Limestone of Croft Farm. In this 

 the pairs of arms or each paired series are only two in number,, 

 while in the new species of Eucladia at least four, and in E. John- 

 soni as many as seven, are present. Eucladia and the new genus 

 are regarded as aberrant Ophiurids, and are placed in a new order 

 as a group of the same value as the Euryalae. They are defined 

 as Ophiurida possessing paired series of arms, covered externally by 

 imbricating plates, but devoid of ambulacral ossicles. The buccal 

 armature is abnormal. 



2. " Note on the Occurrence of Sponge-spicules in the Carboni- 

 ferous Limestone of Derbyshire." By Prof. W. J. Sollas, M.A., 

 LL.D., D.Sc, F.R.S. 



Remains of sponge-spicules are fairly abundant in a rock-slice 

 taken from a specimen obtained by Mr. H. H. Arnold -Bemrose from 

 Tissington cutting. They present themselves as sections through 

 long cylindrical rods, but the terminations are obscure and 

 indefinite, and the form cannot be referred with certainty to any 

 recognized order of Sponges. The spicules were doubtless originally 

 siliceous, but they are now completely transformed into carbonate of 

 lime. Rhombohedra of calcite appear to have completed their 

 growth as readily within the spicule as outside it, and the final 

 result of the corrosion is to entirely replace the opal of the spicule 

 by a congeries of minute crystals of calcite. As the crystals may 

 have begun their growth outside the spicule, the latter rarely 

 preserves its characteristic regular outlines. The crystals being 

 frequently bounded by impurities of the limestone, the spicules are 

 often as clearly defined as corresponding structures in the Chalk. 



3. " On Spinel and Forsterite from the Glenelg Limestone." By 

 C. T. Clough, Esq., M.A., F.G.S., and Dr. W. Pollard, M.A., F.G.S. 

 (Communicated by permission of the Director-General of H.M. 

 Geological Survey.) 



The paper opens with an account of previous literature on the 

 subject of minerals in the Glenelg limestone. Neither forsterite 

 nor true spinel has been previously recorded from the limestone or 

 from Scotland at all. The three or four bands of limestone which 

 make their appearance on Sheets 123 and 127 of the 6-inch 

 survey of Ross-shire are probably the same bed repeated by isoclinal 

 folds. The banded gneisses, schists, and eclogites among which the 

 limestones occur are separated from the sheared and inverted Torri- 

 donian rocks on the west-north-west by flaggy granulitic quartzite 



