67 



But In Carboniferous times there were five great flowerless groups, 

 all of which are illustrated here. Of these, three, the Spheno- 

 phy Hales, ^ the Pieridospernis, and the Cordaitales, became totally^ 

 extinct millions of years ago. The other two, the LycopodiaUs and 

 the Eguiseiales, have still a few survivors to-day in our Club- 

 mosses and Horsetails, though they are now scanty remnants of what 

 in Carboniferous times were very large and complex groups. 



The asterisk (J^) denotes the name of the authority who first described 



the species. 



THE LYCOPODIALES. 



Our first group includes the ancient Palaeozoic representatives of 

 our Club-mosses. Unlike the present-day survivals of this group, 

 the Carboniferous Lycopods were large trees, often leo feet or mora 

 in height. There are four common genera, the stems of which are 

 known as Lepidodendron, Lepidophloios, Sigillaria, and 

 Bothrodendron, as well as cones (Lepidostrobus) and under- 

 ground stems or rhizome* (Stigmaria). 



LEPIDODENDRON. 



Page 6. Lepidodendron sp. Part of a branch just beginning 

 to fork above. The branch is covered with the persistent bases of 

 the fallen leaves, which give it a characteristic appearance. The 

 leaves were spirally arranged and closely set. When the leaves fell 

 off, their lozenge-shaped bases remained attached to the stem. 

 From the Yorkshire coalfield. | natural size. 



Page 7. Lepidophyllurn sp. Detached leaves of a Lepido- 

 dendron or an allied genus. The leaves are quit* simple. Ihey 

 may be long or short, straight or curved, but are always narrow, and 

 possess only a single nerve, which is clearly seen in the photograph. 

 In this specimen the leaves are long and straight. From the 

 Somerset coalfield. X |. 



Page %. lyepidodendron aculeatum, Sternberg.* Part of a 

 stem similar to that shown on page 6, enlarged to show the form of 

 the leaf-bases characteristic of this species. The leaf-bas«s are 

 separated by sinuous bands of bark. A little above the middle of 

 each leaf-base two scars can be seen, the lower being the actual 

 point of attachment of the leaf itself, known as the leaf scar, the 

 upper and smaller, the triangular scar of the " ligule," which was a 

 small outgrowth from the base of the leaf. Below the leaf-scar, the 

 leaf-base has a marked longitudinal ridge witk several small trans- 

 verse ridges. From the Yorkshire coalfield. X f. 



Page 9. Lepidodendron lycopodioides, Sternberg.* Another 

 common species, in which tlie shape of the leaf-bases is quite 

 distinct from the last. The leaf-scar is small and is situated near 

 the top of the leaf-base. From the Cumberland coalfield. X 2. 



Page 10. Lepidodendron Wortheni, Lesquereux.* A third 

 species, quite distinct from the preceding in the form and ornamenta- 

 tion of the leaf-bases. From the Somerset coalfield. X 2. 



Page n. A transverse section from a petrified Lepidodendioid 

 stem, showing one type of internal structure. There is no pith. 

 In the centre the primary wood is seen, which is surrounded by 

 an incomplete and uneven ring of secondary wood. 'J'he dark ring, 



