A6 BRITISH FOSSIL CRUSTACEA. 
On tHe Discovery, BY Mr. Rosert Siimon, or Fossi~s IN THE UPPERMOST SILURIAN 
Rocks, NEAR LESMAHAGO, IN SCOTLAND, WITH OBSERVATIONS ON THE RELATIONS 
oF THE PaLmozoic Strata IN THAT PART OF LaNaRKsHIRE. By Sir RopERICK 
Impry Murcuison, D.C.L., F.R.S., V.P.G.S.. AND DirEctor-GuNERAL 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. Shmon 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 
Pterygoti, 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 Pferygotus 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 
