192 LYCOPODITES, PTILOPHYTON, PSILOTITES. 



surprising that he has found imitators. Thus two species, Ps. gracillimum, 

 Lesq. and Ps. cornutum, Lesq., from the Silurian deposits of N. America, 

 have been described by Lesquereux 1 and are fit associates of Dawson's 

 Ps. elegans. A fossil form from the Lower Devonian beds of Rhenish 

 Prussia was described by Goppert 2 in his time under the name of Hali- 

 serites Dechenianus and placed among the Algae. Its delicate tufts of 

 branches by their incurved hooked extremities recall Psilophyton princeps, 

 though they are quite smooth and have no lateral thorns. Dawson 3 first 

 removed this form conjecturally to his Psilophyton, and Carruthers 4 has 

 since followed his example. The latter author has moreover added to the 

 same group certain fossils from the Devonian Sandstone of the north of 

 Scotland, which were originally described as Lycopodites Miller! 5 , and 

 which if judged by the figures do in fact show some resemblance to Psilo- 

 phytae. Carruthers names them Psilophyton Dechenianum, Carr., and 

 unites Haliserites with them. In like manner Sphenopteris Condrusorum, 

 Gilk., which has been already noticed, was first described by Crepin 8 as a 

 species of Psilophyton. Lastly, as we are on the subject of these ancient 

 and obscure remains, we may mention here the very recently published 

 Berwynia Carruthersii 7 from the Middle Silurian deposits of Corwen in 

 Wales, which has been supposed to be the stem of a Lycopod of great 

 dimensions. In spite of the good accompanying figure I would rather not 

 express any opinion respecting either this fossil, or Drepanophycus spini- 

 formis 8 from the Upper Devonian Spiriferae-Sandstone of Hachenburg in 

 Nassau, which to some extent resembles Berwynia. 



Of the group of Isoeteae we know only two Miocene forms found at 

 Oeningen and strongly recalling our Isoetes lacustris, for which it will be 

 sufficient to refer the reader to Schimper 9 . Solenites Murrayana, Lindl. and 

 Hutt, from the Oolite of Scarborough, will be found noticed in the same 

 work as a doubtful form. This fossil has been excellently described in 

 Lindley and Hutton 10 . It consists of long linear pointed leaves lying 

 together in tufts and found in large numbers on certain slabs of stone. 

 According to the "figure, the epidermis, which was brought out by treatment 

 with nitric acid, is formed of irregularly angular cells, between which no 

 stomata were observed. This would certainly agree with the structure of 

 the submerged Isoetae; but fresh examination of the facts with the better 

 means now at our disposal is much to be desired, since the tufts of leaves in 

 Solenites may quite as well be supposed to be short shoots of Conifers like 

 those of Phoenicopsis and Czekanowskia, and then stomata must certainly be 

 found on the leaves. Something also might be gained from an examination 



1 Lesquereux (5). * Goppert (12), t. 2. * Dawson (1). ' Carruthers (9). 



5 Salter (1). Crepin (1). T Hicks (2). Goppert (12), t 41, i. 9 Schimper (1). 

 10 Lindley and Htitton (1), vol. ii, t. 121. 



