VOL. xvn. (3) FOSSIL PLANTS— FOREST OF DEAN 327 



those of other coalfields, but they have yielded very complete 

 and excellent specimens of several plants, especially of Calamo- 

 cladus equisetijormis (Schloth.), Plate XXXVII. , fig. 5, and of 

 species of Sigillaria and Alethopteris. Most of the species 

 common in this coalfield can be obtained here, notably Neurop- 

 teris ovata, Hoffm., Plate XXXVII., fig. 6, Pecopteris poly- 

 morpha, Brongn., Plate XXXVII., fig. 3, and Pecopteris Mil- 

 toni (Artis), Plate XXXVII., fig. 2 Among the rarer plants 

 are Alethopteris Grandini (Brongn.), Plate XXXVII., fig. 4, 

 A.davreuxi (Brongn.), A. aquilina (Schloth.), Plate XXXVIII., 

 fig. 10, and Plate XXXIX., fig. 13, Sigillaria rugusa, Brongn., 

 Plate XXXVIII., fig. 8, and the very rare S. trigona, Sternb. 



PARKEND COLLIERY 



Parkend Colliery in the Southern part of the Forest has 

 also furnished a fair number of plants, including Catamites 

 ramosus, Artis and Annularia sphenophylloides (Zenker). 



The Third Division Coals 



Of the six coals of the Third Division, only the Yorkley, 

 the Coleford High Delph and Trenchard Coals are of workable 

 thickness. The higher beds of this series are alternations of 

 shales and sandstones, but, below the Yorkley Coal, the strata 

 consist of massive sandstones, which yield the well-known 

 Forest of Dean Stone, which is so largely exported from the 

 Forest. These beds are quarried in many parts of the Forest. 

 There are several very large quarries, on or near the road 

 from Speech House Road Station to Coleford. One of them. 

 Oak Quarry, must be over 200 feet deep and consists almost 

 entirely of massive sandstones. This essentially arenaceous 

 series is one of the most striking features of the Productive 

 Measures of the Forest. Unfortunately these sandstones do 

 not contain fossil plants, or rather, where such impressions 

 occur, they are too badly preserved to be recognisable. In 

 only one case have fossil plants been obtained from above the 

 Coleford High Delph Coal, and here it happened that, by an 

 almost unheard-of occurrence, a small bed of shale suddenly 

 appeared above the coal, as we shall see presently. 



