THE GLOSSOPTERIS FLORA. 183 



trace bundles. There are also reasons for believing that 

 the stem of Glossopteris bore two kinds of leaves, the 

 ordinary tongue-shaped fronds and much smaller scale 

 leaves. Zeiller compares StriUhiopteris Gerinanica and 

 Olemidra with Glossopteris, both as regards the arrangement 

 of leaves on the stem and the distribution of vascular 

 strands in the rhizome. 



In spite of the fact that in some districts beds of rock 

 extending over a wide area are literally made up of Glos- 

 sopteris leaves, these are almost without exception de- 

 tached fronds and not attached to any stem structure. In 

 Africa beds of shale are frequently found to be almost 

 entirely made up of Glossopteris fronds, and in Australia -^ 

 beds of clay have been described as owing their foliation 

 to the close packing of the leaves of this fern. In 1849 

 Dana"^ figured an example in which several fronds appeared 

 to be given off from a stem fragment, and another 

 specimen has now been figured by Etheridge^ from New 

 South Wales. In the latter case several lanceolate fronds, 

 which agree in outline with Glossopteris linearis McCoy, and 

 G. Clarkei Feist., are attached to the apex of a comparatively 

 broad stem. The surface of the stem is covered with 

 crowded leaf-scars, and an internal cast shows numerous 

 narrow protuberances which probably represent the leaf- 

 trace bundles. The general appeaijafiice of the stem does 

 not agree at all closely with that of Vertebi'-aria, which 

 Zeiller has shown to be the rhizome of some forms of Glos- 

 sopteris. It is probable, therefore, that there was more 

 than one form of rhizome bearing true Glossopteris leaves. 



The wide distribution and extended greoloo'ical rano-e of 

 Glossopteris in the Southern hemisphere is a fact well 

 known to geologists, and of considerable interest from the 

 point of view of the distribution of fossil plants, and the 

 development of ancient floras. The term Glossopteris 

 flora originally proposed by Neumayr, has come to be 

 employed for an assemblage of plants ranging from the 

 Upper Palaeozoic to Lower Mesozoic strata, and char- 



1 Dana, p. 716. ^ Dana, pi. xii., fig. 13 C. " Etheridge (3). 



13 



