CHAPTER XLII. 



GENERA or UNCERTAIN POSITION. 



In this section are included several Palaeozoic genera most of 

 ivhich have beeti assigned to the Ginkgoales on evidence which in 

 most cases is ivholly inadequate. 



Probably the oldest specimens referred to the Ginkgoales are 

 some imperfect leaves from Middle Devonian rocks in Bohemia 

 described by Potonie and Bernard as Barrandeina Dusliana 

 (Krejci)^ but there is no evidence of affinity to this or to any other 

 class of plants. 



GLOTTOPHYLLUM. Zalessky. 



This designation has recently been proposed by Zalessky^ for 

 Schmalhausen's Permian species Ginkgo cuneata which has no 

 substantial claim to be regarded as generically identical with 

 Ginkgo hiloba. Zalessky considers that it may belong to the 

 Ginkgoales though the available data hardly justify more than a 

 suggestion of possible relationship. 



Glottophyllum cuneatum (Schmalhausen). 



A Permian species from the Altai mountains* represented by an 

 obovate spathulate leaf 11 cm. long and 4 cm. broad with a compara- 

 tively long ' stalk ' consisting of a narrow portion of the lamina : 

 the lamina is traversed by slightly spreading veins about 1 mm. 

 apart. In form this leaf resembles the genus Eretmophylluni* (cf. 

 fig. 658) and may be a species of that genus^ but in the absence 

 of any information with regard to the epidermal features it is 

 inadvisable to adopt a name implying affinity to the Ginkgoales. 



1 Potonie and Bernard (04) p. 45. 



2 Zalessky (12=) p. 28 (footnote). 



» Schmalhausen (79) A. p. 34, PI. iv. fig. 5, 

 « Thomas, H. H. (13). 



