136 Guide to Fossil Plants. 



GAILEBT Dudley and other localities are of extremely doubtful affinity ; 

 ^ probably some of these should be included in the Animal Kingdom. 



18* T bT^ The genera Nematophycus and Pachytheca are of some interest as 



case 32. being the oldest fossils described as plants in which the internal 

 structure has been preserved; the former was probably a large 

 seaweed, but the nature of the latter is more doubtful. The 

 genus Berwynia, from Corwen (N^orth Wales), is in all probability 

 a mineral structure, and not the remains of any organism. 



In the same cases there are some excellent specimens of the 

 oldest known British fern, Palceopteris Hibernica, from the Devonian 

 rocks of Kiltorkan, near Waterford. The genus Psilophytoiiy 

 especially characteristic of the Devonian strata of Canada, is 

 represented by several imperfect examples : the true nature of 



Wall-caaes this plant is not certainly known. In Table-cases 31 to 26, and 



15-18, ill the Wall-cases 15 to 18, there is a very good series of fossils 



Table- . •' ° 



cases illustrating the more characteristic and striking plants of the 



31-28. Upper Caeboniferous forests. The large polished section of a 

 tree {Araucarioxylon) between the Wall-cases 16 and 17, was 

 cut from the tall stem standing in the grounds of the Museum, and 

 found many years ago in a sandstone quarry at Craigleith, near 

 Edinburgh. In anatomical structure the stem resembles fairly 

 closely the living genus Araucaria, and was possibly the trunk 

 of the extinct genus Cordaites. Thin sections of the wood of this 

 tree are shown in Table-case 31. Casts of the discoid pith of 

 Cordaites^ formerly described as a separate genus, Sternhergia, or 

 Artisia, are among the common Coal-measure fossils; the col- 

 lection also includes several of the long and parallel- veined leaves 

 and flowers of this genus. The common genera Lepidodendron and 

 Sigillaria are abundantly represented ; the well-known Stigmaria 

 is generally regarded as the root of these trees, and is especially 

 characteristic of the underclays of the Coal measures. The cones 

 of the former genus are known as Lepidostrohm, and are frequently 

 met with in the shales and ironstones. The genera Ulodendron and 

 Balonia represent cone-bearing branches of Lepidodendroid plants. 



In some of the table-cases a few microscopic slides are ex- 

 hibited, illustrating the wonderful perfection in which many of 

 the Coal-period plants have had their minute structure preserved. 

 From an examination of their anatomy it has been found that 

 many of the forest trees in the Carboniferous period were near 

 allies of our small living Lycopodiums ("club-mosses"), Equisetums 



