318 PROF. A. C. SEWARD AN±> MR. J. WALTON ON [vol. lxxix, 



distinguish with confidence between stems of Phyllotheca, Schizo- 

 neura, Neocalamites, and Equisetites. Equisetites, a genus 

 widely spread in the Triassic and Jurassic floras of the Northern 

 Hemisphere, is characterized by leaf-sheaths Avith short, free teeth 

 which usually lie close to the surface of the stem as in the recent 

 Equisetum, and the vascular strands of adjacent internodes are 

 alternate. In Phyllotheca the leaf-sheaths are similar to those 

 of Equisetites and Equisetum, but the}' are often less closely 

 appressed to the stem, and the individual leaf-lamina? are longer 

 and more spreading. Moreover, in Phyllotheca, Schizoneura, and 

 Neocalamites the vascular strands usually, though not invariably, 

 pursue a straight course from one internode to the next. We 

 believe that several of the specimens obtained by Dr. H. A. Baker 

 bore leaves of the Phyllotheca type, but no complete leaf-sheaths 

 have been seen on any of his material. On the other hand, we 

 have no doubt that some specimens of Equisetaceous stems cannot 

 be included in that genus. 



(A) Equisetaceous stems. Cf. Phyllotheca australis Hvong- 

 niart. (PL XIX, figs. 3, 4, & 6 ; PL XXI, fig. 16 ; text-fig. 2.)— 

 Several specimens undoubtedly identical specifically with the steins 

 referred by Dr. Halle to Phyllotheca australis were obtained by 

 Dr. Baker from George Island and other localities. In view of 

 the careful description already published, it is unnecessary to deal 

 Avith the additional examples in detail. The impressions of the 

 basal portions of leaf-sheaths are often well preseiwed, and these 

 bear a striking resemblance, in the flat ribs separated by narrow 

 grooves or ridges, to the sheaths of Equisetum. We have not 

 detected any free laminae, either as detached fossils or connected 

 with the sheaths. The fragment reproduced in fig. 4 (PL XIX), 

 nearly twice the natural size, shows a practically smooth surface: 

 close to a very slight nodal constriction there is a row of small 

 projecting points which may represent a whorl of slender branches. 

 As Dr. Halle points out, M'Coy described branching stems in 

 the Australian Phyllotheca HooJceri M'Coy, a species generally 

 regarded as identical with Ph. australis. 



Both Nathorst and Halle compare some of the Falkland speci- 

 mens with Phyllotheca deliquescens (Gceppert) from the Permian 

 deposits of Russia. We are inclined to regard the slightly larger 

 examples of Equisetaceous steins, which agree closely with those 

 compared by the Swedish authors to the Russian species, as insepar- 

 able from the specimens included in Phyllotheca australis. In 

 one of Schmalhausen's figures 1 some slender branches are seen 

 attached to the node of a fairly large stem with prominent ribs and 

 grooves on the internodal surface. The piece of stem shown in 

 fig. 6 (PL XIX), rather more than twice the natural size, has 

 regular ribs and grooves above the node ; and on the grooves are 

 fine longitudinal striations which probably indicate wood-elements. 



1 Schmalhausen (79) p]. x, fig. 1. (The flora, described by Schmalhausen 

 as Jurassic, was shown by R. Zeiller to be probably of Permian age.) 



