1^ 



each node, and between the ridges of the internode, a ring of small 

 scars may be seen. These are termed the infranodal canals, and 

 their size and shape is made use of in distinguishing between the 

 species of pith-casts. From the Warwickshire coalfield. | natural 

 size. 



P^gc 53' Gaiamites approximatus, Brongniart.* Another 

 species of pith-cast with short internodes, and occasionally, as at 

 the top of the photograph, a much longer internode, bearing several 

 branch-scars just above the node. From the Cumberland coalfield. 

 Slightly reduced. 



Page 54. Calamites varians, Sternberg.* A sandstone pith- 

 cast of a species, the internodes of which vary in length. 

 Branch-scars may occur on a single node, separated by several 

 internodes from the next branch-bearing node, as in the last 

 specimen. From the Yorkshire coalfield. Reduced -f . 



Pag® 55- Annularia stellata (Schlotheim).* The leaves of 

 all Calamites were borne in whorls at the nodes of the stems. 

 In the Annularia type of leaf- whorl, the leaves are united into a 

 small collar or sheath at the base. The free portions of the radiating 

 leaves are of unequal length. Each leaf has a single nerve, and in 

 this species the leaves are narrowly lance-like in form. Three 

 whorls belonging to three nodes are seen in this photograph. From 

 the Somerset coalfield. . X f . 



Page 56. Calamocladus equisetiformis (Schlotheim).* The 

 phtograph shows four whorls of leaves still attached to the 

 nodes of a branch. In the Calamocladus type of leaf-whorl the 

 leaves are entirely free at the base from each other, they are nearly 

 equal in length and very narrow, needle-like in shape. From the 

 Somerset coalfields X %, 



Page 57. Calamostachys (.?) typica, Schimper.* Several 

 cones, or organs oi fructification, of a Calamite. The bracts and 

 sporangia can be distinguished here and there. From the Canonbie 

 coalfield. X f 



THE SPHENOPHYLLALES. 



The Sphenophyllales were an important Pa'seozoic group, which 

 to-day is quite extinct. The stems were very slender and herbaceous, 

 and were segmented, like those of the Calamite, into nodes and inter, 

 nodes. The nodes were swollen, and the internodes bore longitudinal 

 ridges separated by grooves. The leaves were characteristically 

 wedge-shaped, hence the name Sphenophylluin. They were borne 

 in whorls of six,, or some multiple of three, at the nodes. 



Page 5S. Sphenophyllum emarginatum, Brongniart.* A 

 slender stem, bearing three whorls, each of six wedge-shaped leaves. 

 The broad apex of the leaf is toothed. A nerve runs to each tooth, 

 and all the nerves unite at the base of the leaf. From the Somerset 

 coalfield, x f 



Page 59. Sphenophyllum emarginatum, Brongniart.* In the 

 centre of the photograph a stem is seen. This is the external sur- 

 face, and the nodes and internodes are clearly marked. The nodes 

 are somewhat swollen. Other fragments of stems, and. numerous 

 leaf-whorls and leaves, are scattered over the specimen. From the 

 Somerset coalfield. Slightly enlarged. 



