230 Botanical Society of Edinburgh. 



the occurrence of scalariform, pitted, and punctated vessels. He 

 was disposed to think that porous vessels had been in some instances 

 mistaken for true punctated woody tissue, which is characterized by 

 the presence of a circle and a dot in the centre. The presence of 

 Sigillarice and StigmaricB in coal, and the conversion of their outer 

 portion into carbonaceous matter, clearly showed that these plants 

 were concerned in the formation of this material. He did not agree 

 with those who supposed that coniferous wood alone formed coal, nor 

 with those who thought that certain rings which appeared on sections 

 of coal parallel to the plane of stratification were the ends of woody 

 tubes. Various plants appear to have joined to form coal, which 

 may account for the differences in the appearance of different parts 

 of the same bed. Specimens were shown of Parrot coal enclosing 

 numerous thin seams of Cherry coal. The extensive fern vegetation 

 of the carboniferous epoch was probably connected with a paucity of 

 other species, and seems to indicate a uniformity of temperature 

 throughout a large area. Many plants, however, which are consi- 

 dered as Ferns, or allied to Ferns, may prove to be Gymnosperms. 



True punctated coniferous structure may be seen occasionally in 

 coal, but it must be borne in mind that this tissue occurs in other 

 plants, such as Winter acece^ and that tissue very much resembling it, 

 and apt to be confounded with it, has also been detected in many other 

 orders. Much is still wanting to enable a fossil botanist to speak 

 decidedly in regard to the true nature of many of the coal plants. 

 In many coals evident sporangia have been detected in large quantities. 

 These resemble the spore-cases of Lycopods. In Fordel coal 

 these sporangia are in vast abundance, and they are associated with 

 Middletonite. 



The varieties of coal are very numerous. There is a gradual pass- 

 age from Anthracite to Household and Parrot Coal ; and the limit 

 between coal and what is called bituminous shale is by no means de- 

 finite. Judging by chemical products, as well as by microscopical 

 and other characters, there seems no reason for separating Boghead 

 or Torbane, Capeldrae, Methil, and other brown Parrot coals from 

 the category of true coals. Dr. Fyfe has instituted careful analyses, 

 by which he showed that Boghead Gas Coal and Boghead Household 

 Coal yield the usual coal products, viz. ammoniacal liquor, tar, 

 naphtha, benzole, naphthaline, grease oil, pitch oil, paraffine and 

 pitch. As to bitumen, a matter soluble in naphtha, this exists in 

 very small quantity in coals, and is less abundant in Torbane coal 

 than in English caking coal. Dr. Fyfe states that in — 



Per cent. 

 Capeldrae coal there is of matter soluble in naphtha . O'O 



Torbane black coal 1-2 



Torbane white coal 1*4 



Lesmahagow 2'33 



While in English caking coal it is 4' 2, 5-8, and even 8 per cent. 



According to Dr. Fyfe, the following are some of the results as 

 regards volatile matter and coke :»*iioi xn 



