656 REPORT— 1894. 



rusty brown material containing crystallised quartz. This rusty-coloured material 

 occasionally weathers out as nodules 8-10 mm. in diameter, projecting 10-15 mm. 

 beyond the white surface of the rock. In other places this rock contains lenticles 

 and concretions of calcareous matter of considerable size, with concentric structures 

 around some of them. When interbedded with slate it is densely studded with 

 small rusty brown spots, sometimes irregular and sometimes of such forms as would 

 be yielded by rhombs ; they are undoubtedly pseudomorphs after carbonate. It has 

 in places all the appearance of a stratified rock, and is distinctly bedded. In one 

 locality this rock assumes a nodular form, with the outer edges composed of spheru- 

 lites varying from 2 to 10 mm. in diameter. The central portions of the spherules 

 are composed of crypto-crystalline material, the outer portions of radiating blades 

 or prisms of felspar, presumably albite. Ferric oxide is scattered through the rock 

 in irregular patches, in veins, or in radial streaks between the blades of felspar, or 

 occasionally it is almost wholl}' concentrated in the polygonal sutures formed by 

 the mutual interference of adjacent spherulites. 



The greenstone is posterior to and intrusive in this soda rock, and cuts across, 

 bends, and disorders its beds. Extreme crushing has in places altered the original 

 junction line, and thrust planes and fault breccias are seen. Quartz veins traverse 

 both rocks, but are more numerous in the soda rock. 



The slate is interbedded on the northern side of the headland with bands of 

 blue limestone, and is occasionally studded with ferruginous patches and nodules 

 in much the same way as the soda rock. 



A rock containing as much as 7'54 per cent of soda is said by Kayser to occur 

 as a contact product due to greenstone in the Ilartz. The question ariaes. Is this 

 Dinas Head rock an adinole or a soda felsite — i.e., a keratophyre ? The presence 

 of ferriferous carbonates favours the theory of its being an altered sedimentary 

 roclv, whilst the spherulitic and concretionary structure favours the theory of its 

 being an igneous rock. 



6. Report of the Committee on Geological Photographs, 

 See Reports, p. 274. 



SATURDAY, AUGUST 11. 

 The following Reports and Papers were read : — 

 1. Seport of the Committee on Palaeozoic Phyllopoda. — See Reports, p. 271. 



2. Report of the Committee on the E^vrypterid-bearing Deposits of the 

 Pentland Hills. — See Reports, p. 302. 



3. Preliminary Note on a New Fossil Fish from the Upper Old Red 

 Sandstone of Elginshire. By R. H. Traquair, M.D., F.R.S. 



These remains consisted of large broad thick plates gently hollowed in boat- 

 like fashion, and showing no articular surfaces along any of their free margins. 

 None of these plates had been found entire, though pieces had occurred of over a 

 foot in length and a quarter of an inch in thickness. To these plates the author has 

 given the name of Megalaspis Tai/lori, 



