TRANSACTIONS OF THE SECTIONS. 61 



to suggest to the Government Survej' a return to the nomenclature •which he was 

 the first to propose, and of which he now vindicates the justice and propriety. 



In this way (and this way only) can there be an end of controversy. The groups 

 will have their first names, and their right geographical names. While the rocks of 

 Cambria are called Cambrian, the rocks of Siluria will be called Silurian ; and not 

 so much as one single bed of rock will be seen out of the limits of the true Silurian 

 colours of the Geological map, of which bed the right place had been fixed in the 

 original sections and details of the ' Silurian System.' 



Finally, the author contends that the most recent and mature works of great Con- 

 tinental and American palaeontologists (such as Barrande, D'Orbigny, Hall, Rogers, 

 &c.) do not invalidate, but confirm, the views here communicated to the British As- 

 sociation. These authors have not, indeed, ever entered on any formal discussion of 

 British palaeozoic nomenclature. They have taken the British groups and names as 

 they found them published ; and naturally left their final adjustment to British geo- 

 logists. But they have presented the data in a form clearly showing the general 

 equivalency of the so-called ' Lower Silurian ' to the Cambrian rocks ; and the re- 

 sults which they have obtained appear, not only to the author of this communica- 

 tion, but also (as he can aflSrm) to some of the great American geologists themselves, 

 to confirm in all important points the physical and palaeontological separation between 

 the Cambrian and Silurian series. 



The author ended by stating, as an excuse for the very great and unusual length 

 of his paper, that he believed it, out of comparison, the most important communica- 

 tion he had ever made to the British Association. It contained historical and geo- 

 graphical details, and several illustrative sections (of which little or no notice is taken 

 in this abstract), and exhibited conclusions derived from evidence, the unfolding of 

 which had taken many years of hard field-labour. And as some of its conclusions 

 were still controverted, they were, on that very account, specially fitted for a calm 

 discussion in the Geological Section (of the British Association), in which he had, at 

 this meeting, the honour to fill the Chair, 



On Pseudomorphous Crystals in New Red Sandstone. 

 By H. E. Strickland, M.A., F.G.S. 



These pseudo-crystals were cubical projections from the under surfaces of laminsB 

 of white sandstone, of the age of the red marls, and had been detected at various 

 localities in Gloucestershire, Nottinghamshire, and Cheshire. They might have been 

 formed in cavities left by the decomposition of iron pyrites, or by the removal of 

 crystals of common salt. That the latter was really the case seemed evident from 

 some of the specimens, in which the faces of the cubes were concave, and exhibited 

 concentric lines. The author inferred that the crystals of salt were formed on, or in 

 the mud of the shore, during a temporary exposure to the sun, and being again 

 covered by the sea, the crystals had dissolved, and their form had been assumed by 

 the material of the next succeeding deposit. 



On some Ayrshire Fossils. By Wyville T. C. Thomson, LL.D. 



Dr. Thomson exhibited a collection of fossils from the Lower Silurian (or Cam- 

 brian) rocks, on the South bank of Girvan Water, in Ayrshire : they were obtained 

 by breaking up the rock, and still retained their natural surfaces in very great per- 

 fection ; whereas, fossils of the old rocks in general only retain their real surfaces 

 when developed by the weather. 



On Refracted Lines of Cleavage seen in the Slate Rocks of Ballyrizora, in 

 the County of Cork. By R. W. Townsend, M.A., M.R.I.A. 



The author exhibited a diagram representing the surface of some Devonian rocks 

 near Cork, in which the angle of the cleavage planes changed slightly on passing 

 from the argillaceous layers to those of a more arenaceous character. — [The subject 

 had been already examined by Prof. Phillips, and discussed at the Meeting of the 

 British Association at Cork, in 1843.] 



