576 PTERIDOSPERMS, ETC. [CH. 



A. Serlii is very abundant in the Upper Coal-Measures but 

 rare in the Middle Coal-Measures of Britain^. 



Lonchopteris. 



This name was proposed by Brongniart^ for sterile fronds 

 from Upper Carboniferous rocks which are practically identical 

 with species of Alethopteris, but differ in the reticulate venation 

 of the pinnules. It has been pointed out in a previous chapter* 

 that Lonchopteris is usually used for Palaeozoic species, the 

 Wealden leaves, which were placed in this genus by Brongniart, 

 being transferred to Weichselia. 



There can be little doubt as to the close relationship of 

 Lonchopteris with Alethopteris: both may be referred to the 

 Pteridosperms. Lonchopteris rugosa Brongn.'' (fig. 290, B, p. 399) 

 and L. Bricei Brongn., both British species, are fairly common 

 in Upper Carboniferous strata. In L. rugosa, a Middle Coal- 

 Measures species, the anastomosing secondary veins form poly- 

 gonal meshes (fig. 290, B, p. 399) smaller than those of L. Bricei, 



Pecopteris. 



Reference has already been made to this genus in the 

 chapter on Marratiales, so far as regards certain species of 

 fertile fronds the sporangia of which resemble those of recent 

 Marattiaceae. It is, however, by no means safe to assume that 

 such Pecopteris fronds were borne on stems having the anatomi- 

 cal characters of ferns. The sporangia in some at least of the 

 species may have contained microspores. In one Upper Car- 

 boniferous species usually referred to Pecopteris, P. Pluckeneti^ 

 Schlot., Grand'Eury* has recorded the occurrence of seeds on 

 the pinnules of the ordinary fronds. This species will be 

 referred to in Volume ill. The substitution of such generic 

 names as Ptychocarpus, Asterotheca, Hawlea, Dactylotheca 

 and others for the purely provisional designation Pecopteris 

 indicates a step towards a conclusion as to natural affinity. 

 The probability is that Pecopteris, as applied to Palaeozoic 



1 Kidston (94) p. 245. 2 Brongniart (28) A. p. 59. 



» Page 494. •> Kidston (94) p. 596. » Grand'Eury (05). 



