VI] 



SPHENOPSIDA 



75 



evidence perhaps no certain evidence at present. Attention 

 may however be drawn to some very obscure fossils which may 

 conceivably have some bearing on this point. At the same time 

 it must be freely admitted that these bodies are extremely 

 obscure and that no emphasis can be laid on them from this 

 point of view. There do, however, occur in the Ordovician, 

 Silurian and Devonian rocks, carbonaceous impressions which 

 in some respects recall the Annular! an leaves of Calamites. They 



Fig. 41. Protannularia laxa, (Daws.), from the Upper Devonian 

 of Canada (f nat. size). After Dawson (1871). 



have in fact more than once been referred to Annularia itself. 

 Perhaps the best specimens of this nature are those described 

 by Dawson 1 from the Devonian of Canada as Annularia laxa, 

 Daws. (Fig. 41). 



Dawson 2 states that "the ends of the leaves are curled in a 

 circmate manner" and he figures them as each possessing a vein. 

 It may be also recalled here that many years ago Nicholson 3 



1 Dawson (1871), p. 31, PL VI, fig. 64; cf. also figs. 65-69. 



2 Ibid. (1871), p. 81. 



3 Nicholson (1869), p. 495, PI. 18, fig. B; Nicholson and Lydekker (1889), 

 p. 1514. 



