212 MR ROBERT KIDSTON ON 



nerve and the obscurity of the secondary veins — which distinguish this form from the 

 normal plant. The fructification also differs very little, the limb of the fertile pinnae 

 and pinnules, at least on the fossil figured on pi. ii. fig. 2, is much more reduced than 

 on the fructifying specimens which I have had from the Middle Coal Measures, but 

 perhaps these differences depend simply on the degree of development, and possibly one 

 should not attach too great an importance to them." 



" The sporangia are coriaceous, without any trace of an annulus, they possess all the 

 characters of the genus Dactylotheca, and they differ from the sporangia of normal 

 Pecopteris clentata only in that they are broader and shorter, and, in consequence, 

 less tapered, — they are also more numerous and more closely placed the one to the other, 

 and they appear to be disposed without any order." 



These differences, as suggested by Zeiller, may only represent a greater advance in 

 maturity or a greater development of sporangia. He further refers to a similar occur- 

 rence in many species of Asplenium, where, when the fructification is very much 

 developed, they cover the whole of the lower surface of the limb.* 



Probably some of my Yorkshire specimens belong to the same form, such as that from 

 which the sporangia were drawn, shown on my pi. ii. fig. 14. Here the sporangia, from 

 their number and close position to each other, appear as if placed without order. In my 

 figure the rows marked a' and a" probably represent the sporangia of one pinnule, and 

 were borne on the secondary veins. 



My fig. 2, pi. i., is apparently the barren condition of Zeiller's var. obscura. 



Corresponding with Zeiller's figure of the var. obscura given on his pi. ii. fig. 2, is 

 probably my fig. 7, pi. ii. This figure only shows a small portion of a fruiting specimen, 

 which is the Bphenopteris crenate, L. and H., so far as the portion figured is concerned, 

 but the upper barren portions of the pinnae not shown in the figure, possess all the 

 characters of Dactylotheca plumosa. They are quite similar to my fig. 13, pi. iii., only 

 not in so good a state of preservation. 



Pecopteris {Dactylotheca) Gruneri, Zeiller. 



Zeiller describes in his Flore fossile : Etudes sur le terr. houil. de Comentry,^ a 

 Dactylotheca under the name of D. Gruneri, of which he gives drawings of both the 

 barren and fruiting condition. 



This species is certainly very closely related to Dactylotheca plumosa, if really 

 specifically distinct from it. 



Comparing it to Pecopteris dentata (which is synonymous with Pecopteris plumosa), 

 he says : — "Pecopteris Gruneri, when compared to the Pecopteris dentata ,is distinguished 

 by the thickness of its limb, by its pinnules less distinctly lobed, more rounded at the 



* Sterzel, in Die Flora des Rothliegenden im Plauenschen Grunde bei Dresden (Abhandl. d. k. Sax. Gesell. d. Wissen. 

 Math. Phys. 01., vol. xi.w, Leipzig, 1893), p. 37, pi. v. figs. 1-G, describes another variety of Pec. dentata under the name 

 of var. Saxonica. 



t Page 104, pi. x. figs. 1-2, 1888. 



