pagiophtlltjm:. 49 



Vegetative shoots mouopodially branolied, bearing crowded, 

 spirally disposed, fleshy leaves. The leaves vary in shape andi 

 position ; they are usually hroadly triangular, sometimes reaching 

 a length of 5 mm., imbricate and fairly closely appressed to the 

 stem ; in some shoots they are more open in arrangement and more 

 distinctly falcate. The back of the leaves bears a broad median' 

 keel, and the lamina is frequently characterised by numerous 

 longitudinal striations or -wrinklings ; the apex of the leaf may 

 be obtuse or acuminate. 



Flowers not known. 



Among the specimens included under this type one notices 

 differences as regards the shape and disposition of the leaves which, 

 however, are not of sufficient importance to justify the use of 

 more than one specific name. 



The occurrence of leaves having different shapes on branches 

 of the same tree is not an uncommon phenomenon among recent 

 Conifers, and there can be little doubt that too much weight has 

 been attached to slight variations as regards leaf -form ia the deter- 

 mination of fossil coniferous twigs. Arauca/ria, perhaps, is more 

 constant in the shape and disposition of its leaves than some 

 other recent genera, but cases of heterophylly ' are by no means 

 unknown. 



It is probable that Pagiophyllum peregrinum represents the 

 vegetative branches of an Araucarian tree. Lindley & Hutton 

 recognised the resemblance of the Lias specimens from Lyme Eegis 

 to Araucaria exceha, and adopted the generic name Arauearia ; 

 linger, Eurr, Goppert, and some other authors have also used 

 this generic name or Araucarites. A good drawing by Adolphe 

 Brongniart of an English specimen from Lyme is published by 

 Saporta in the third volume of his Plantes Jurassiques ; 

 Saporta notices a difference as regards habit between the fossU 

 branches and those of recent Araucarias. It is true that the habit 

 of branching, as shown in PI. V. Fig. 4, and in the specimen 

 figured by Saporta, is not quite the same as in Arauea/ria exceha, 

 but the recent species A. Irasiliensis agrees closely with the 

 liiassic form as regards the disposition of the smaller branches. 



' Siebold (70), pi. 140 ; Potoni^ (99), p. 292, fig. 295. 



