: 



XLl] PHOENICOPSIS 69 



Feildenia Nordenskoldi Nathorst. 



A species from Upper Jurassic rocks in Spitzbergen founded by 

 Nathorst 1 on leaves similar to those of F. rigida but smaller ; the 

 lamina is generally 3 4 mm. broad and may reach a length of 

 4-5 cm. There are usually six veins and as in other species finer 

 longitudinal lines occur between the true veins. A few small 

 leaves very similar to F. Nordenskoldi are described by Nathorst 

 as Feildenia sp. 2 from Franz Josef Land, probably of Wealden age. 



Until further evidence is available it is impossible to fix pre- 

 cisely the position of the genus. Though often distinguished by 

 the sickle-shaped lamina and the broad apical region from leaves 

 of Podozamites it is not always possible to separate the leaves of 

 the two genera. . 



PHOENICOPSIS. Heer. 

 DESMIOPHYLLUM. Lesquereux. 



Phoenicopsis was founded by Heer 3 on linear leaves from 

 Middle Jurassic strata in Siberia ; the leaves, in extreme cases 20 cm. 

 long and varying in breadth from 2 mm. to 2 cm., occur in clusters of 

 six or more and even as many as twenty on very short and relatively 

 broad axes covered with small scale-leaves. These dwarf-shoots 

 were deciduous : the lamina is fairly uniform in breadth but tapers 

 gradually towards the slender base and is usually obtusely rounded 

 at the apex ; the veins are parallel and very rarely dichotomously 

 ranched. The features on which species are founded are often 

 of little systematic value : they are the breadth of the lamina, the 

 arrangement of the veins, the presence or absence of interstitial 

 veins.' It is very doubtful whether much confidence can be 

 laced on the occurrence of the so-called interstitial veins: in 

 me species of Phoenicopsis the parallel veins show no trace of 

 smaller 'vein' between them, but occasionally in a leaf of the 

 me species there are indications of interstitial 'veins.' The 

 readth of the lamina is also an uncertain guide : well preserved 

 pecimens show that the leaves may reach a considerable length 

 nd that the lamina gradually decreases in breadth towards the 

 arrow base. Species have been needlessly multiplied particularly 



1 Nathorst (97) p. 56, PL m. figs. 1627. 



2 Nathorst (99) p. 15, PI. i. figs. 2530, 32. 3 Heer (77) ii. p. 49. 



