JEFFREY. — NATURE OF SOME SUPPOSED ALGAL COALS. 283 



cal metamorphosis, and only faint lines of alveolation indicate the na- 

 ture of the original organization. Through the kindness of M. Bayle, 

 Director of the Compagnie Lyonnaise des Schistes Bitumineux, I have 

 received an abundant supply of the boghead from Autiin, containing 

 the organism described by Renault and Bertrand under the name of 

 Pila bibractensis. These samples came both from the beds of Mar- 

 genne and Th(^lots. It is an unfortunate circumstance, which beyond 

 question has had a bearing on the views as to the nature of boghead 

 coals, that the first of these to be minutely studied, viz., that of Autun, 

 is characterized by structural elements, which are obviously in an 

 extremely bad condition of preservation. In none of the material 

 which has passed under my observation have I found the component 

 structures well organized. This seems to have been the condition of 

 the material studied by Renault, to judge from the figures published in 

 the atlas accompanying his work cited above. Some of the vertical 

 sections published by Bertrand, however, present a better condition of 

 preservation. This is notably the case in the reproduction of one of 

 Bertrand's figures in Potonie's work on coal cited at the beginning 

 of this article.^ The accompanying horizontal aspect of the coal, how- 

 ever, presents the usual bad condition of preservation. Figure 24, 

 Plate 4, shows a somewhat highly magnified vertical section of the 

 boghead from Autun. In the lowermost of the organisms there is some 

 indication of the presence of a central cavity. The walls of the struc- 

 tures in question are all in a swollen condition. Figure 25, Plate 5, 

 shows a number of the individuals of Renault's Pila bibractensis un- 

 der a low magnification. It may be stated in general of the boghead 

 of Autun, that it is largely composed of organisms, which are in a dis- 

 integrated and swollen condition and which are consequently hard to 

 interpret. It seems particularly unfortunate that this boghead was 

 •the first to be carefully studied microscopically. 



Oil-Shale of New South Wales. 



Figure 26, Plate 5, illustrates the structure of the oil-shale of New 

 South Wales in section vertical to the plane of layering. This bog- 

 head, like those of Torbane Hill and Balbardie, Scotland, is almost 

 completely made up of the organisms interpreted by Renault as Algae 

 and named Reinschia australis. The organisms are generally not 

 completely flattened in this plane of section and are often very much 

 distorted and folded. The usual absence of complete flattening of the 

 micro-organisms in bogheads composed very largely or almost entirely 



^ Potonie, op. cit., p. 23, fig. lib. 



