xxxix] 



PTILOPHYLLUM 



519 



because they are less appressed to the rachis while the lower half 

 of the base is closer to the rachis and is frequently, though not 

 in Morris's specimen, overlapped by the upper edge of the next 

 lower pinna. A re-examination of the type-specimen in the 

 British Museum confirms this interpretation. The pinnae of 

 Ptilophyllum are characterised by their attachment to the upper 

 face of the rachis which they almost 

 completely cover; the upper angle is 

 rounded and in a few cases auriculate 

 (fig. 592) ; the lower angle of the base 

 is slightly rounded and not infrequently 

 hidden by the imbrication of the 

 adjacent pinna; it is occasionally 

 auriculate (fig. 593). The pinnae are 

 attached by nearly the whole base, 



but the upper angle is free. The veins are parallel, sub- 

 parallel or, especially in the proximal portion of the lamina, 



Fig. 592. Ptilophyllum pecten. 

 (Manchester Museum, William- 

 son Coll. 3726.) 



Fig. 593. 



Ptilophyllum pecten. 

 Yorkshire. 



From the Lower Estuariue 

 (After Thomas; nat. size.) 



beds, Cleveland, 



oblique. The pinnae are linear, varying considerably in relation 

 of length to breadth and in the form of the apex ; they are Straight 

 or more or less falcate. The epidermal cells of such Ptilophyllum 



