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XVI. —On a New Species of Dineuron and of Botryopteris from Pettycur, Fife. 

 By R. Kidston, LL.D., F.R.S., F.R.S.E. (With One Plate.) 



(Read May 4, 1908. MS. received same date. Issued separately August 25, 1908.) 



Among the interesting specimens which have been yielded by the material of 

 Calciferous Sandstone age (Culm), from Pettycur, near Burntisland, are a petiole of 

 Dineuron and a very small species of Botryopteris. The former genus does not appear 

 to have been previously discovered in Britain, and the present species is, as far as I am 

 aware, only represented by a single example. The Botryopteris, in the form of 

 fragments of petioles, is not infrequent, but its stems are of much more rare occurrence. 



I. Dineuron ellipticum, Kidston, n. sp. (Plate, figs. 1-3.) 



The specimen which forms the subject of the following description consists of a 

 single transverse section of an almost circular petiole, whose greater width is about 

 2*25 mm. (fig. 1). 



The petiole possesses an outer zone of stout cortex about 0'60 mm. wide (fig. 1, o.C), 

 which is succeeded inwards by a narrow band of delicate inner cortex (fig. 1, in.C). 

 This was separated by an endodermis (fig. 1, end.) from the thin-walled elements of 

 the stele, which have almost entirely disappeared, and the mass of xylem now lies on 

 one side of the space which they originally occupied (fig. 1). 



The xylem of Dineuron ellipticum consists of an elliptic mass whose greater 

 diameter is about 070 mm. It is composed of large tracheae without any admixture of 

 parenchyma ; towards its two extremities the tracheae suddenly become smaller where they 

 meet the protoxylem elements (fig. 2, prx.). 



At the right side of the xylem mass, a short distance within its margin, is a circular 

 opening surrounded by the protoxylem elements. According to Renault, this circular 

 opening was originally filled with parenchyma,* which also occurs in a similar position 

 in the stele of Zygopteris duplex, Will., sp.t \ 



At the left side of the stele a semicircular sinus is observable. This results from 

 the separation of a portion of the xylem to form the outgoing pinna trace. There is, 

 unfortunately, no clear evidence as to the mode of departure of the pinna trace, for the 

 structure so interpreted by Renault in his Dineuron pteroides\ is more probably an 

 unequal division of the petiole stele. One can only suggest, from the great similarity of 

 the stele of Dineuron to that of Zygopteris duplex, that a band was cut off alternately from 



* In Dineuron pteroides, Renault, Bassin houil. et perm. d'Autun et d'Spinac, Flore foss., deux, part, p. 22, 1896. 



t Rachiopteris duplex, Will., Phil Trans., vol. clxiv., p. 687, Plates. 



| Several slides of Zygopteris duplex in my collection show this : Nos. 1315, 1314, 1313, etc. 



§ Renault, I.e., p. 23, fig. 19. 



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