PSILOPHYTON, ISOETITES. 189 



Lycopods ; but this cannot be determined without study of the original 

 preparations. 



A series of very dubious remains from the Devonian and Carboniferous 

 deposits of North-Eastern America has recently been grouped together by 

 Dawson l under the name Ptilophyton, Daws. Hall has described the same 

 objects as hydroid polypes and given them the name Plumalina ; in 

 Lesquereux 2 they are called Trochophyllum and are appended to Cala- 

 mariae. The species first discovered, Ptilophyton Vanuxemi, Daws., which 

 had been already figured by Vanuxem 3 , appears in Dawson's earlier publi- 

 cations 4 as Lycopodites Vanuxemi, and with it a form from the Lower Coal- 

 measures of Canada as L. Plumula 5 . This author also introduces into his 

 genus L. pennaeformis 6 from the Millstone Grit of Altwasser in Silesia, 

 which is known in one piece only and is of a very questionable character. 

 The specimen unfortunately was not to be found for the moment, when I 

 was in Breslau. Little can be gathered from Dawson's and Lesquereux's 

 somewhat rough figures ; specimens of the American forms do not appear 

 to have reached Europe. These are thin branches with a striated surface 

 and crowded verticillate scars : and on these branches and on both sides of 

 them are linear leaves (?) which are still in situ and very nearly form a right 

 angle with the branch, and which in the drawing of Ptilophyton lineare, Lesq. 

 look almost like the needles of Coniferae. Dawson it is true does not state 

 that the leaves are verticillate : he says ' slender leaves in two or more ranks.' 

 The character of the surface in the stem figured by Lesquereux is strikingly 

 suggestive of the remarkable and little-known Equisetum mirabile noticed 

 above on p. 178, and it was this resemblance which led him to place this 

 form with Calamariae. In conclusion, I must express my doubts as to 

 whether all these objects thus grouped together by Dawson do really belong 

 to one another ; and I am confirmed in these doubts by the circumstance 

 that Lesquereux in the work in which he describes Trochophyllae reckons 

 Lycopodites Vanuxemi 7 among Lycopodiaceae, with the remark it is true 

 ' It may be an Encrinite,' without thinking of comparing them. 



The statements respecting fossil remains of the family Psilotaceae are 

 few and uncertain, nor is this surprising in such simple and slightly differ- 

 entiated forms. If Psilotites lithanthracis 8 and Ps. unilateralis 9 do really 

 belong to this group, a point which I am unable to determine from the' 

 figures, we should be able to follow the type as far down as the period of 

 the Coal-measures. 



It has become more and more a settled practice with palaeontologists 

 and botanists to unite the genus Psilophyton with Psilotaceae 10 . Dawson 



1 Dawson (1), vol. ii, p. 119. 2 Lesquereux (1), p. 63. 3 Vanuxem (1). * Dawson 



(1), vol. i, p. 35. 5 Dawson (7), p. 24; t. i, ff. 7-9. 6 Goppert (19), p. 508; t. 42. 



7 Lesquereux (1). p. 362. " Goldenberg (1), t. 2, f. 7. 9 Kidston, 3. 10 Dawson (I), (5), (6). 



