JEFFREY. — NATURE OF SOME SUPPOSED ALGAL COALS. 279 



outer wall of the spore. In juxtaposition to the body, which is clearly 

 a spore, are two of the putative Algae. In Figure 11, Plate 2, is shown 

 another view of a spore-like body, there more obviously a spore. On 

 the left is the projecting internal face of the spore, seen in sec- 

 tion as an angle. The back of the spore is sculptured. In the re- 

 mainder of the field are a number of the Alga-like bodies. The mag- 

 nification in the present figure is about one half greater than in the 

 last. Figure 12, Plate 2, represents, together with a number of the 

 putative Algae, a body with the same alveolar parietal structure, which 

 is at the same time obviously a spore. Figure 13, Plate 3, shows one 

 of the spores so mumerous in the boghead coal under examination, in 

 face view. The three ridges which mark the surfaces of contact with 

 the three originally present sister spores of the tetrad can be very clearly 

 made out. Such clear views of the spore face are comparatively rare, 

 whether from the condition of compression of the spores or from the loss 

 by decay of the thinner angular inner face of the spore, it is not easy 

 to determine. The outlines of the spore in the last figure are rough, 

 showing the alveolar nature of the free surface resembling that found 

 in the spores of many of the existing Lycopodiales. Figure 14, 

 Plate 3, shows in the center another spore in the same plan of section 

 as that in the last figure. The magnification is very much higher for 

 the purpose of bringing out the rough surface of the spore shown on 

 the margins of the figure, particularly on the lower side. Above and 

 below the central object are small portions of two other spores appear- 

 ing as mottled alveolar structures. Figure 15, Plate 3, shows a com- 

 plete tetrad of the spores under consideration in an oblique plane of 

 section, which partially passes through the tetrad and partially reveals 

 its free surface. Of three spores appearing in the section through the 

 tetrad, two show at least part of their rough outer surface, while in 

 case of the third none of this is apparent. 



It will probably be apparent to the unprejudiced reader, from the 

 figures of free spores and tetrads of spores in various planes of section 

 already shown, that the supposed Alga, Pila kenturkyana of Renault, 

 as figured in Figure 4, Plate 23, of his monograph, in reality represents 

 sections through the rough alveolar surface of the reproductive bodies 

 of vascular cryptogams. Although the conclusion thus indicated seems 

 clear from the examination of reasonably numerous and well-prepared 

 sections of coal containing the species under discussion, I have not 

 allowed such evidence alone to suffice. As explained in the introduc- 

 tion, numerous serial sections were cut, in which it was possible to fol- 

 low the appearance of the imagined Algae as well as the obvious 

 spores as seen in successive planes. On account of the compression of 



