88 GENERA OF UNCERTAIN POSITION [CH. 



in Tasmania which he compares with G. Grasserti Sap., but as he 

 gives no illustration of the fossil no opinion can be formed of its 

 true nature. 







Psygmophyllum kiltorkense Johnson (^ Kiltorkensia devonica John.). 

 A species 1 recently described from the Upper Devonian grits 

 of Kiltorcan, Ireland, characterised by fan-shaped leaves 7 cm. 

 long and 5 cm. broad, deeply divided into two symmetrical halves 

 each of which is again divided into two ribbon-like segments with 

 a Ginkgo-like venation. The leaves agree closely with those of 

 P. Grasserti in their general form and in the lobing of the lamina. 

 Johnson believes this type to be an ancestral form of Ginkgo 

 though there are no adequate grounds for such a view. 



Psygmophyllum ? crenatum (Brauns). 



The close resemblance presented by the Rhaetic leaves from 

 near Braunschweig, originally described by Brauns 2 as Cyclopteris 

 crenata and subsequently figured by Nathorst 3 as Ginkgo ? crenata, 

 to some Permo-Carboniferous leaves included in Psygmophyllum 

 suggests affinity with that genus. The obovate lamina, approxi- 

 mately 12 cm. long, is slightly lobed on the upper margin and 

 contracted below into a stalk-like base; the forked veins are 

 nearly 3 mm. apart. Nathorst compares the species with Psygmo- 

 phyllum flabellatum Lind. and Hutt., but the Rhaetic specimen 

 differ from the English type in their much coarser venation : in 

 the lobing of the lamina and in the coarse venation there is a much 

 greater similarity to the broader leaves described by Arber 4 as 

 Psygmophyllum majus. In view of the incomplete nature of the 

 material it is inadvisable to adopt the name Psygmophyllum 

 without reservation. An examination of Nathorst 's specimen in 

 the Stockholm Museum led me to regard it as more probably an 

 example of Psygmophyllum than of Ginkgo. 



1 Johnson (14). Since this account was written Prof. Johnson has described 

 additional material including stems and foliage [Johnson (17)] demonstrating the 

 occurrence of repeatedly forked filamentous leaves [or leaflets] attached to slender 

 axes bearing also the broader form of lamina. The plant, which he now refers to 

 a new genus Kiltorkensia, may well be a Pteridosperm with compound fronds and 

 dimorphic pinnules. 



2 Brauns (66) p. 52, PL xm. fig. 8. 3 Nathorst (78). 

 * Arber (12) p. 392, Pis. XLII. XLIV. 



