244 ponozAMiTES. 



the. pinnse the attachment appears to he rather on the upper f aoe- 

 of the raohis. The veins are numerous and parallel, as in the- 

 Cycadean genus Zamites. The specimen is not sufficiently well 

 preserved to enable us to determine the exact manner of attachment 

 of the pinnse, and it is veiy doubtful if all of them are shown in 

 their original position. It is probable that the pinnae of this species- 

 wore deciduous and separated from the rachis by a definite 

 separation-surface, and this circumstance adds to the danger of 

 assuming that all the leaflets are in their original positions.' 



The considerable amount of variation in the size and form of 

 the segments has given rise to the institution, by Heer and other 

 authors, of several varietal terms, but it is improbable that the 

 numerous so-called varieties were borne by distinct plants. It 

 would seem that the species is characterized by a marked tendency 

 to variation in the form and dimensions of the linear-lanceolate 

 segments. A specimen in the York Museum, which cannot 

 reasonably be separated specifically from the ordinary type such 

 as is represented in Text-fig. 44, illustrates this variability. The 

 pinnae in the York specimen are approximately 4 mm. in breadth ; 

 they are arranged on the shale at unequal distances apart, and 

 attached by a narrow base to the slender rachis. 



Among the numerous specimens figured by Heer from Jurassie 

 rocks of Siberia and Spitzbergen, there are several which appear 

 to be identical with Podozamites lanoeolatus (L. & H.), and others- 

 with broader segments (e.g. P. pulohellus'^) which represent another 

 specific type. 



We find several Rhaetic examples of Podozamites'^ referred to- 

 such species as P. lanoeolatus, P. distana, P. Mnmonsi, and others, 

 which appear to be almost, if not quite, identical with the type- 

 species of Lindley & Hutton ; it is clear that this plant was one 

 of the most widely spread elements in both the Ehsetic and Oolite 

 floras. 



39,303. Text-fig. 44. 



This specimen has a length of 17'5 cm. from the base to the tip 

 of the highest leaflet. The preservation is unfortunately not very 



' Seward (00), p. 16. 



' Heer (77), vol. iv. (1), pi. ix. fi^'s. 10-14. 



» Vide Nathorst (7«) ; Sclienk (67) ; Fontaine (S3), pi. xxxiii. fig. 2, etc. 



