70 



Plate 25, Stigmaria ficoides (Sternberg), On the left hand 

 side, part of an underground stem v/ith its oval scars like that on 

 page 24 is seen, to which several rootlets, running out to the right, 

 are still attached. From the Newcastle coalfields Slightly reduced. 



Plate 26. Transverse sections of petrified specimens of Stij::'- 

 vtaria. The section below is from an underground stem. There is 

 a large central pith, the tissue of which is not preserved, and then a 

 bread ring of wood, which is characteristically divided up into 

 bundles. On the outside, on the right of the section, part of the 

 bark or periderm is seen, as a dark band. 



The section above j:uts across two rows of Stigmarian 

 rootlets or appendages, which have a characteristic appearance. 

 Near the centre of each a small circular patch of tissue is seen, 

 which includes the wood and inner cortex. On the outside there 

 is a large ring, the outer cortex, and between the inner patch and 

 the outer ring a white space, which represents the middle cortex, 

 the tissues of which are not preserved. From the S, Lancashire 

 coalfield. X f. 



THE PTERIDOSPERMS AND FERNS. 



Fern-like fronds or leaves are very common in the Coal Measures, 

 but many of them belonged to plants which bore seeds (Pteridos- 

 perms) and were thus not of the same nature as the modern ferns. 

 The fronds are classified according to their shape and nervation, as 

 they nearly always occur detached from the stems and seeds. 



SPHENOPTERIS. 



The name Sphenopteris is applied to fronds, which are much 

 branched (compound) and bear small leaflets, usually much lobed, 

 cut, or divided, and as a rule contracted at the base. The nerves 

 are simple or branched. 



Page 27. Sphenopteris Honingfhausi, Brongniart.* Avery 

 important species, studded with glandular hairs, the prints or scars 

 of which can be seen on the main axis shown in the photograph. 

 The leaflets are small and typical of a Sphenopteris. This frond 

 bore seeds {Lagenestonta). From the South Durham coalfield. 

 Reduced to | natural size. 



Page 28. Sphenopteris obtusiloba, Brongniart,* and S» 

 furcata, Brongniart.* The former species, which is one of the 

 commonest, shows the lobed leaflets, contracted at the base, which is 

 characteristic of the Sphenopterids. The letter species, geen near the 

 bottom of the photograph on the right band side, has more deeply 

 divided and much narrower leaflets. From the Cumberland coal- 

 field. X I, 



Page 29. Sphenopteris neuropteroides (Boulay).* A fourth 

 species in which the lobes of the leaflets are very bread. From the 

 Forest of Dean coalfield. X |. 



Page 30. Transverse section ©fa petrified stem of Lyginodendron 

 oldhamium (Williamson), which bore the frond Sphenopteris 

 Honinghausi (Page 2j). In the centre, a. dark patch marks the 

 position of th« pith. Outside this is a broad ring of secondary wood. 

 On the inner margin of the secondary wood and the outer margin of 

 the pith, there were five small groups of primary wood, which can just 

 b« made out. Outride the ring of secondary wood, a dark, circular 



