part 3] FOSSIL PLANTS FROM THE FALKLAND ISLANDS* 



319 



On the node circular branch-scars are clearly seen. A little below 

 the node part of a leaf-sheath is preserved : broad flat surfaces lie 

 above the grooves on the lower level of the cast, and the smooth 

 flat surfaces are separated by narrow grooves in each of which is a 

 narrow ridge. The broken edge of the leaf-sheath is seen at S, 

 fig. 6. The combination in this specimen of features shared by 

 both forms of stem figured by Nathorst and by Halle lends support 

 to our view that all the examples described by the Swedish authoi^s 

 are specifically identical, a view supported also by the branched 

 specimen described by Schmalhausen. It is, however, hardly 

 possible to say whether or not the Russian type is separable by any 

 clearly defined vegetative characters from Phyllotheca australis. 



Fig. 3 (PI. XIX) represents part of an incomplete stem 205 cm. 

 long, with internodes from 3*5 to 5 cm. long, and having a maxi- 

 mum diameter of 2 - 2 cm. The ribbing of the internodes is rather 

 irregular, and at the nodes are branch-scars. This specimen 

 resembles closely the larger specimens figured by Nathorst and 

 Halle, and we see no reason for separating it from the smaller 

 branches with leaf-sheaths. Part of a similar stem is shown some- 

 what diagrammatically in text-fig. 2. It is 3"5 cm. broad, and 



Fig. 2. — A cast of part of a rhizome of an Equisetaceous plant 

 (cf Phyllotheca australis Prong ni art) showing roots at the 

 nodes. Half of the natural size. 



the internodes are nearly 4 cm. long. There are indications of 

 branch-scars on the middle node. The interesting feature of this 

 specimen is the occurrence at two of the nodes (at a and b) of 

 slender, branched appendages which we believe to be roots. Pro- 

 bably the specimen is part of an underground rhizome which bore 

 aerial shoots agreeing with those of Phyllotheca australis. 



The small portion of a medullary cast reproduced in fig. 16 

 (PI. XXI) shows very clearly a nodal constriction, the charac- 

 teristic correspondence of the ridges and grooves on the two sides 

 of the nodes, and the impression on the internodal ridges of long 

 and narrow wood-elements. 



(B) Equisetaceous stems. Cf. Neocalamites Carrerei 

 (Zeiller). (PL XX, figs. S, 10, 12.)— Some of the recently-obtained 

 steins differ in their larger dimensions, and particularly in the 



