Spencee, : Geology of the Halifax Hard Bed Coal. 3 



supplement and localise the excellent lecture given by my friend Mr. 

 Butterworth lest month. My friend and colleague, Mr. Binns, will 

 show you sections, of his own preparing, of the plants which I shall 

 bring before you, all from your own locality. Many and many a 

 Saturday afternoon have we spent together collecting these specimens, 

 but on him has devolved the labour of preparing them for the micro- 

 scope ; how far he has succeeded I will leave you to form your own 

 judgment when you have seen them. The two most common plants 

 we find in the coal balls are Lepidodendron selaginoides, Sigillaria 

 vasctilaria (of Binney), and L. Rarcourtiiy their round and perfect 

 stems being frequently met with. It is a most singular fact that, 

 although Sigillaria is one of the most common fossils met with in the 

 coal formation, its well-known form being met with in all sandstone 

 rocks, in shale, and in ironstone, about 40 species being known, yet 

 WG rarely find it in the coal balls so preserved as to show the 

 structure of the whole stem, in the same manner as we find the 

 Lepidodendron. The cortical layer or bark is often met with ; I have 

 found some five or six different specimens. The Stigmaria, which is 

 the root of the Sigillaria, is very abundant, and often well preserved. 

 A vertical section of the bark, showing the manner in which the 

 rootlets come out of the stem, is a very beautiful object. The 

 structure is well shown in a transverse section. The Lepidodendron and 

 Sigillaria belonged to the clubmoss family ; the tallest clubmoss in 

 the world does not exceed five feet in height, but these ancient club- 

 mosses attained the girth and altitude of our modern forest trees. 



I will next call attention to the Calamites — a class of fossil 

 plants which belong to the same family as the horsetails of our 

 ditches. You are all familiar with the sandstone cast which goes by 

 that name, and of which I hold in my hand a fine sample. But this 

 does not represent the plant itself, only the cast of its interior. The 

 bark was smooth, not ribbed as the cast is. First we have a cortical 

 layer of cellular tissue, then a woody zone, which consisted of a 

 number of vascular wedges, the interstices of which were filled with 

 cellular tissue, while the interior was hollow, except at the nodes. 

 When the plant died, the cellular tissue between the wedges rapidly 

 decayed, and the spaces, along with the centre, became filled with 

 sand, hence these casts present a more or less ribbed appearance. 

 The woody zone became mineralised into coal — which is the thin 

 black smudge that always accompanies them when first disinterred by 

 the quarrymen. The Aster ophylUtes was closely allied to the Cala- 

 mites. The section of the Zygopteris is a splendid object. It seems 



