﻿46 BRITISH FOSSIL CRUSTACEA. 



On the Discovery, by Mr. Robert Slimon, op Fossils in the uppermost Silurian 

 Rocks, near Lesmahago, in Scotland, with Observations on the Relations 

 op the Palaeozoic Strata in that part op Lanarkshire. By Sir Roderick 

 impey murchison, d.c.l., f.r.s., v.p.g.s., and dlrector-general of the geo- 

 LOGICAL Survey. 



(Reprinted, by permission, from the 'Quarterly Journal of the Geological Society of London ' for 1856, 



vol. xii, pp. 15 — 19.) 



"Introduction. — At the last meeting of the British Association [in 1855], Mr. Robert 

 Slimon brought to Glasgow two remarkable collections of fossils from the extensive 

 parish of Lesmahago, in which he practises as a surgeon. One of these collections was 

 derived from the bands of Carboniferous Limestone, which there alternate with Coal, and 

 are characterised by a great abundance of fine specimens of Producti, Encrinites, Corals, 

 and other remains peculiar to deposits of that age. The other consisted of specimens of 

 Crustaceans in dark-coloured schist or flag, and to two or three specimens of which 

 my attention, as President of the Geological Section, was fortunately called by Mr. David 

 Page. The magnificent collection of Mr. R. Slimon had, in fact, remained almost 

 unobserved, in a hall which few geologists visited. 



" The moment I cast my eye over these remarkable Crustaceans, which much resembled 

 Pteryyoti, and saw the matrix in which they were imbedded, it occurred to me that they 

 probably pertained to the Uppermost Silurian zone. It became, therefore, necessary to 

 visit the locality in question, chiefly for the purpose of ascertaining the physical relations 

 of the dark schist with large Crustaceans to the Old Red Sandstone. For, as I was aware 

 that the genus Pteryyotus had been found as low in the Silurian rocks as the Upper 

 Caradoc band, it might prove that there was the same great hiatus near Lesmahago as 

 had up to this time been supposed to prevail all over Scotland, and that no representative 

 of the Uppermost Silurian existed. On the other hand, the band in question might 

 prove to be that which I shall endeavour to show it is, viz. the true representative of the 

 highest Silurian zone, as developed in Herefordshire, Shropshire, and Westmoreland in 

 England, in Russia on the Continent of Europe, and also in North America. 



" Having requested Prof. Ramsay to accompany me, we visited Lesmahago to- 

 gether, and there found, to our gratification, that the worthy and modest Mr. Slimon 

 had not only a much richer collection of the fossils in question than he brought to 

 Glasgow, but had also an accurate acquaintance with many of the prominent and detailed 

 features of the tract. Guided by him to the best natural sections, and particularly to 

 the spot on ' Logan Water,' hitherto famous only in Scottish song, where he had found 



