CRITICAL STUDIES OF COAL-MEASURE PLAN T-IMPRESSIONS, 171 
Critical Studies of Coal-measure Plant-impressions *. By the late E. A. 
NrwzLL AmBER, M.A., Sc.D., F.G.S., F.L.S., Trinity College, Cam- 
bridge, University Demonstrator in Paleobotany. 
(PLATES 8-15 and 2 Text-figures.) 
[Read 15th June, 1922.] 
CONTENTS, 
Page 
I. A Revision of the British Upper Carboniferous Species of the Genus 
Lepidostrobus, Brongn., preserved as incrustations ,............. 171 
II, Lepidodendron lycopodioides, Sternb., L. ophiurus, Brongn., and 
L, lorieatum, sp. nova ..........,,........, eee us 189 
III. Neuropteris obliqua, Brongn., and N. callosa, Lesq. ,............, 207 
List of References ,,,.,,......,.....,....., .,.,............ 216 
I. A Revision of the British Upper Carboniferous Species of the Genus 
LEPIDOSTROBUS, Brongn., preserved as incrustations. 
INTRODUCTION, 
THE genus Lepidostrobus, instituted by Brongniart in 1828 for a particular 
type of Lyeopod cone common in the Coal Measures, is one of the most stereo- 
typed organs known from the rocks of this period. Its general structure, as 
evidenced both by petrifactions and impressions, is too well understood to 
need description here, One of the chief features of this cone, however, is the 
very small range in variation met with, excluding factors of such doubtful 
value as mere size and shape. For this reason the discrimination of species 
has always been a difficult matter, especially in the case of incrustations. 
Among petrified specimens it is known that there is, as a rule, great 
uniformity in type, though Mr. Maslen (21. p. 357) and, at a later date, my 
wife (1. p. 205) have shown that certain variations do occur, some of which 
are probably of sufficient importance to be regarded as of specific rank. 
* (Owing to the death of the Author before these studies were finally revised, I am 
responsible for their present form. I have to acknowledge a grant from the Royal Society 
in aid of the preparation of this and other memoirs left by my husband in various stages 
of completion, The Cannock Chase Colliery Company have also been kind enough to 
contribute £10 towards the cost of the illustrations. I am indebted to the Keeper of the 
Geological Department of the British Museum (Nat. Hist.) and to Prof. Boulton of the 
University of Birmingham, for the opportunity of studying specimens in their charge. 
I wish, also, to express my gratitude to Prof, J. E. Marr, F.R.S., who has given me every 
facility for work in the Sedgwick Museum, Cambridge, where most of the specimens 
illustrated in this memoir will be found.— AGNES ARBER.] 
LINN. JOURN.—BOTANY, VOL. XLVI, o 
