CLA.DOPHLEBIS. 139 



Before referring to other authors whose determinations are 

 mentioned in the above synonymy, it may he a convenience to- 

 concisely summarize the conclusions to which an examination of 

 the East Yorkshire Cladophlebis fronds has led me. 



In the first place it seems almost certain that Pecopteris undans 

 as figured by Lindley & Hutton and others is, as Nathorst suggested, 

 the fertile frond of Cladophlebis denticidata. Further reference is 

 made to this point elsewhere. The comparison of such specimens 

 as that figured by Lindley & Hutton as Pecopteris imignis, the 

 example represented in PI. XIV. Fig. 1 (39,236), and many others, 

 with specimens like that shown in PI. XIV. Fig. 3, and as figured 

 by authors under such names as Neuropteris or Pecopteris ligata, 

 P. tchitbiensts, etc., in which the pinnules are smaller, has con- 

 vinced me of the identity of the fronds possessing larger and smaller- 

 ultimate segments. The prominence or almost complete absence of 

 denticulations on the margin of the pinnules are characters of slight 

 importance. In some cases, as an examination of type-specimens 

 has shown, segments with a finely dentate border have been 

 erroneously represented in drawings as pinnules with an entire 

 margin. In one or two specimens in the National Collection and 

 other museums the pinnules appear to be entire, but in other 

 respects the fronds cannot be separated from those with dentate 

 pinnules. To lay stress on such a point as this would be to 

 magnify a character of very small importance to the rank of 

 a specific difference ; my impression is that on a large frond 

 of the fern Cladophlebis denticuhita, we might well find xmu- 

 pinnules with entire and others with a denticulate border. 

 Brongniart's species Pecopteris Phillipsii, as already suggested, is- 

 probably a somewhat imperfect example of C. denticulata. 



There are certain species of fronds of the Cladophlebis ty in- 

 figured by several authors from Jurassic horizons which present 

 a close agreement with C. dttnticulata, but which cannot with 

 safety be included in a list of synonyms. In Schenk's admirable 

 work on the flora of the strata between the Keuper and the Lias 

 of Franconia a frond is figured as Asplenites Eoesserti (Presl) ; the 

 drawing of this species in Schenk's pi. x. fig. 1 * agrees very 

 closely with specimen No. 39,238 in the British Museum Collection, 

 and still more closely with a specimen in the Leckenby Collection 



1 Schenk (67). 



