290 PAGI0PHYLLUM. 



identical with one of the American forms figured hy Fontaine ; the 

 Potomac species Nageiopsis microphylla, Font., N. descrescens, Font., 

 and others 1 are very similar to the Whitby fragments. 



Text-fig. 51. Whitby Museum, No. 2503. 



This fragment shows clearly the form and disposition of the 

 broadly linear leaves, l^-l'Scm. in length; the axis of the 

 specimen has a length of 3 cm. 



Another specimen (2377) in the Whitby Collection consists of 

 several pieces of branches similar to that shown in the figure ; 

 in one fragment the axis of the shoot is branched, as in the 

 Wealden specimen already referred to. Each leaf is traversed by 

 several parallel veins, which converge slightly towards the point 

 of attachment of the narrow leaf-base. 



? CONIFERS INCERT.E SEDIS. 



Genus PAGIOPHYLLTJM, Heer. 



[Secc. Trab. Geol. Portugal, p. 11, 1881.] 



Saporta 2 and other authors incline to the view that the species 

 included in Heer's genus should be regarded as members of the 

 Araucarineae, but this opinion is based very largely on a similarity 

 of vegetative structures, which does not receive decisive support 

 from such evidence as is afforded hy the more important 

 reproductive structures. While recognizing the possibility of 

 a close relationship hetween this widespread Mesozoic genus and 

 Araucaria, it is safer to regard Pagiophyllum as one of the 

 numerous extinct forms which cannot be safely included in any 

 particular family of the Coniferse. It is difficult to draw 

 a satisfactory line between the genera Pagiophyllum and Elatides, 

 and perhaps the English Jurassic species, which I have placed 

 in the former genus, should rather be referred to Heer's genus 

 Elatides, the name under which Nathorst 3 has recently included the 

 plant described by Lindley & Hutton as Lycopodites Williamsonis. 



1 Fontaine (89), pis. lxxvii., lxxxvi., etc. 

 3 Saporta (84), p. 373. 

 3 Nathorst (97), p. 34. 



