i es.» 
A MONOGRAPH 
OF THE 
BRITISH FOSSIL CRUSTACEA 
OF THE 
ORDER MEROSTOMATA. 
PA RS: ee 
INTRODUCTION. 
GEOLOGY OF LESMAHAGO, LANARKSHIRE. 
As this and the succeeding part of the Monograph will be mainly occupied with 
the description of species of Pferygoti obtained from one locality, namely, the parish 
of Lesmahago, in Lanarkshire, I have thought it not out of place here to prefix a short 
description of the district by Sir Roderick I. Murchison, Bart., who, with Prof. Ramsay, 
visited Lesmahago in 1855, accompanied by Mr. Robert Slimon, for the purpose of 
studying the geology of this locality. 
This account, although written some years since, is in the main confirmed by an examina- 
tion subsequently made by Mr. A. Geikie, F.R.S. (now Director of the Geological Survey 
of Scotland), who, in an admirable paper! (published in the ‘Quart. Journ. Geol. Soc., 
Lond.,’ 1860, vol. xvi, p. 312), traces out the connection of these extreme northern Silu- 
rian deposits with those of the Pentland Hills in Edinburghshire.? (See also ‘ Siluria,’ 
4th edition, 1867, pp. 159—162.) 
I think this description the more necessary inasmuch as the name of the district has 
now become so familiar to all collectors of palzeozoic fossils, by reason of the vast number 
of specimens (chiefly of Crustacea) obtained by Mr. Robert Slimon and his sons, and now 
distributed through the museums and private collections, not only of this country, 
but also of Europe and America. 
1 One of Mr. Geikie’s sections illustrates this Introduction. See page 51. 
2 The officers of the Geological Survey and subsequently Mr. G. C. Haswell, of Edinburgh, have 
discovered remains of Pterygotus and Slimonia in the Upper Silurian rocks of the Pentland Hills. 
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