82 



PAL^ONTOLOGICAL BOTANY. 



Helmsdale, Miller detected about 60 species of plants, in- 

 cluding Cycadacege and Conifera3, with detached cones, and 

 Fern-forms resembling Scolopendrium. He also discovered a 

 species of Equisetum, and what he supposed to be a Calamite. 

 There is an absence of true coal-fields in the secondary 

 formations generally ; but in some of the Oolitic series, as in 

 the lower Oolite at Brora, in Sutherlandshire, and in the 

 north-east of Yorkshire, and the Kimmeridge clay of the 

 upper Oolite, near Weymouth, there are considerable deposits 

 of carbonaceous matter, sometimes forming seams of coal 

 which have been worked for economic purposes.* Some sup- 

 pose that the Brora coal was formed chiefly by Equisetum 

 columnare (Fig. 82). In the sandstones and shales of the 



Yis. 84. 



Fis, 83. 



Fig. 85. 



Oolitic series, especially in the lower Oolite of the north of 

 England, as at Whitby and Scarborough, as well as in Stones- 

 field slate, the Portland Crag of the middle, and the Port- 

 land beds of the upper Oolite, numerous fossil plants are 

 found. Pence Lindleyana is one of the Coniferge of the 

 lower Oolite. Beania (Plate H. Fig. 2) is a Cycadaceous 



Fig. 83. Araucarites sphcerocarpus, Carr., found in the inferior 

 Oolite at Bruton, Somersetshire. 



Fig. 84. Termination of a scale of Araucarites sjjhcerocarjms, Carr. 



Fig. 85. Section of a scale of Araucarites sphcerocarpus, Carr., 

 showing the size and pc^'tion of the seed. 



* Coal in the Kimmeridge clay is probably of animal origin. 



