BICTTOPHTLLTTM. 123: 



BietyopJiyllum, rugosum, but in other species the sporangia are 

 described as having a complete vertical or oblique annulus and 

 tetrahedral spores.'] 



In 1828 Brongniart proposed the name Phlehopteris PMllipsiiox 

 the plant figured by Lindley & Hutton in 1834 as Bictyophyllum 

 rugosum; the latter name is quoted by the French author as 

 a synonym, although the plant was not described in the Fossil 

 Flora until 1834. We must assume, therefore, that Brongniart 

 saw the description by the EngUsh authors some years before- 

 Lindley & Hutton published their work. The name Bictyophyllum- 

 rugosum has been usually accepted, and, apart from the question 

 of strict priority, it is adopted as the better known and more- 

 convenient designation. In a later work, Brongniart^ expressed 

 the opinion that the English species should probably be referred 

 to Presl's genus Camptopteris. 



In 1856 Zigno instituted a new specific name, Bictyophyllum' 

 Leclcenhyi, for a Bictyophyllum frond from the Yorkshire coast, 

 with deeply piunatifid pinnae having long and narrow ultimate 

 segments, which he regarded as distinct from B. rugosum. The- 

 difierence between such a leaf as that shown in pi. xxiii. of Zigno's 

 work and Williamson's drawing published by Lindley & Hutton, 

 consists chiefly in the longer and narrower segments of the former,, 

 but the existence of transitional forms affords ample evidence 

 of the specific identity of the two forms. In 1878 Nathorst' 

 discussed at some length the genus Bictyophyllum, and quoted 

 the species as characterized by very variable leaves and as 

 illustrating the difficulty of distinguishing between species and 

 varieties. 



The relationship of Bictyophyllum rugosum with recent ferns 

 is of considerable interest. The genus Bictyophyllum has been, 

 quoted as a leptosporangiate fern agreeing in certain characters- 

 with both the Gleicheniacese and Cyatheaceoe,'' and in that respect 

 comparable with Matonidium and Laocopteris. Some of the more 

 perfect specimens of Bictyophyllum certainly suggest a comparison, 



> Schenk (67), pi. xvi. 



2 Brongniart (49), p. 32. 



3 Nathorst (78^), p. 13. 



* Solms-Laubach (91), p. 164. 



