THE 
MONTHLY MICROSCOPICAL JOURNAL. 
OCTOBEE 1, 1869. 
I. — On the Structure of the Stems of the Arlorescent Lyco- 
jpodiacese of the Coal Measures. By W. Carruthers, F.L.S., 
F.G.S., Botanical Department, British Museum. 
(" Taken as Read'''' hefore the Royal Microscopical Society, June 9, 1869.) 
(Communicated by the President.) 
Plate XXVII. 
Having for some time been collecting materials for the illustration 
of the stems of Sigillaria, Lefidodendron, and other forms of 
gigantic Lycopodiacem belonging to the Carboniferous period, I 
propose to submit to the Society some account of these remarkable 
structures, and to examine the points of agreement and difference 
between them and the stems of existing plants. 
• I have been especially fortunate in obtaining a large collection of 
fossils from the beds of volcanic ash discovered by E. Wunsch, Esq., 
in the north-east corner of the Island of Arran, in the Frith of 
Clyde. Guided by his son, I had myself the pleasure of exploring 
the beds and of collecting a number of specimens. The rocks are 
exposed on the shore at Laggan, and consist of a considerable series 
of volcanic tufas indurated by infiltrated carbonate of lime, alter- 
nating with thin beds of hardened shales. Stigmarian roots abound 
in the shales, and, with not a little difficulty, I removed the super- 
imposed rock and traced the radiating branches of Stigmaria pro- 
ceeding from a large trunk of Sigillaria. The different beds of 
EXPLANATION OF PLATE. 
Fig. 1. — Transverse section of a portion of the stem of Lepidodendron selaginoides, 
Sternb., from the centre to the circumference, a. the axis. 6. the 
investing cylinder, both composed of scalariform vessels, c. delicate 
parenchyma, more or less decayed, d. stronger parenchyma passing 
into prosenchyma <?, /, outer layer of the prosenchyma. g. the bark. 
h. section through the decurrent base of a leaf. 
„ 2. — Longitudinal section of ditto through tlie centre of the axis. The letters 
refer to the same structures as in Fig. 1. The open space above the 
letter c arises from the decay of the delicate parenchyma ; that above 
the letter d, which passes upwards and outwards, was occupied by a 
vascular bundle and its associated delicate parenchyma. 
„ 3.— One of the cellular rays in transverse section. 
„ 4. — Section of several rays at right angles to their direction. 
VOL. II. O 
