PRE-OARBCNIFEROUS PLANTS. 



67 



K^ 



Petioles OF Ferns. ' ' ' '■ 



96 to 100. Rhachiopteris, viz., (It. pinnata, R. ci/clopteroides, B- 

 punctata, R. striata, R. tenui8triata.)—J. G. S., lb. 



Under this generic name I have described several detached leaf-stalkB 

 of ferns, principally from New York and St. John, of which the fronds are 

 unknown. I have nothing further to add, in respect to these, except that 

 my recent specimens from Gaspe lead me to suspect that some of these 

 supposed leaf-stalks may bo in reality decorticated stems of Psilophyton. 



Several detached leaf-stalks of ferns are in my collections from St. 

 John, but they probably belong to some of the species above described. 

 Though no fronds of ferns have yet been found in the Gasp^ plant-beds, 

 with the exception of the pinnae of Cychpteris Jacksoni already referred to, 

 obecuro specimens are not infrequent, which I think can be distinguished 

 from stems of Psilophyton, and are probably petioles of ferns. One of 

 these is figured in PI. VII., Fig. 80a. 



Two large and interesting specimens of petioles, probably of tree ferns, 

 have recently been communicated to me by Prof. Hall. They are : 



101. Rhachiopteris gigantea. Dn. 



This is the base of a large leaf-stalk somewhat flattened. It is smooth 

 and marked with even longitudinal depressed lines, about twenty in number, 

 dividing the surfaces into rounded ridges. It shows no structure, but has 

 the remains of carbonized fibres or bundles of vessels at the larger end. It 

 is from the Hamilton group (Middle Devonian) of New York. It is three 

 inches in diameter, and must have supported a very large frond. 



102. Rhachiopteris palmata,T>xx. a ; '. ;. v.* 



This is ten inches in length, flattened, and marked with furrows and 

 ridges. It divides at the distal extremity in a palmate manner into five 

 pedicels. From another specimen in Prof. Hall's collection, already 

 referred to, I would infer that this petiole may possibly have borne fronds 

 of the type of Cychpteris Rogersi, It is from the Hamilton group (Middle 

 Devonian,) of New York. 



The number of stipes of ferns found in some of the Devonian beds is 

 instructive, as indicating the amount of maceration which the fronds have 

 undergone. In the Devoaion also as in the Carboniferous, few fronds 

 showing fructificatioa occur. 



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