742 STATE OP THE GLOBE AT THE COAL EPOCH. 



and either remain simple or bifurcate, the neuration or venation being 

 similar to that of some Zamias. 



A fossil plant called Antholites has been found in the coal-mea- 

 sures. It appears to be a spike of flowers, having a calyx and linear 

 petals. Mr. Peach has recently found that the fruit called Cardio- 

 carpum is the produce of this plant (fig. 920). It may possibly be a 

 Monocotyledon. Mr. Peach has also found a peculiar fossil fern near 

 Edinburgh, which presents the characters of the genus Staphylopteris 

 of Lesquereux. 



In the bituminous shale at Granton, near Edinburgh, Dr. Robert 

 Paterson discovered in 1840 a peculiar fossil plant, which he called 

 Pothocites Grantoni (fig. 921). It is a spike covered by parallel 

 rows of flowers, each apparently with a 4-oleft perianth. It was sup- 

 posed to be allied to Potamogeton or Pothos, more probably to the 

 latter. In that case it must be referred to the natural order Aracese. 

 Pothocites has been recently found by Mr. Etheridge near West 

 Calder, and by Mr. Bennie at Oorstorphine, near Edinburgh. Lygino- 

 dendron (Xuyivog, wicker-work) is a peculiar coal fossil discovered by 

 the Eev. Mr. Landsborough in Ayrshire, and described by Mr. Gourlie. 

 Its impression consists of rounded narrow twigs, which cross each 

 other like the parts of an osier basket. Lyginodendron (called also 

 Dictyoxylon by Williamson) is probably allied to Lycopods. It has a 

 stem composed of pith, wood, and bark. The parenchymatous pith is 

 surrounded by an irregular vascular cylinder, which breaks up into 

 bundles, separated by medullary parenchyma. Before this, however, 

 the true ligneous zone appeared as a narrow vascular ring, with radiat^ 

 ing vertical laminse, separated from each other by large cellular rays. 

 A bark exists in the circumference formed of two cellular layers, and 

 a third composed partly of parenchyma and partly of prosenchyma. 

 Two species are described by Williamson, Lyginodendron Oldhamia 

 and D. Grievii. 



It may be remarked, in general, that the Carboniferous flora is 

 uniform, or nearly so, in all parts of the globe where carboniferous 

 fossUs have been obtained — viz. the whole of western, northern, and 

 eastern Europe, North America, from Alabama to Melville Island, 

 various districts of Asia, Eastern Australia, and Van Diemen's Land, 

 and probably the Asiatic Islands. 



As fossils in the coal formation consist principally of ferns and their 

 allies, conjectures have been made as to the climate of the globe at that 

 epoch. Ferns of the present day thrive best in a moist insular climate, 

 and many of them occur in tropical climates. Hence Brongniart conjec- 

 tures that at the coal epoch the surface of the earth consisted of a series 

 of islands in the midst of a vast ocean, and that the temperature was 

 higher generally than that of the present day. In the forests of these 

 islands lofty Lepidodendrons would occur, with their delicate and 



