510 Proceedings of the Royal Physical Society. 



XL. On the Fructification of two Coal-mcasLire Ferns. By 

 PvOBErxT KiDSTON, F.R.S.E., r.G.S. [Plate XXL] 



(Read 18tli April 1888.) 



Crossotheca, Zeiller, 1883. 



Crossotheca, Zeiller, Ami. d. Sc. Nat., 6® ser., Bot., vol. xvi., p. 180 ; id., 

 Flore foss. d. bassin houil. d. Valenciennes, p. 33, fig. 21. 



Sorotheca, Stur, Zur Morph. u. Syst. d. Culm- u. Carbon-Farne, p. 175 ; id., 

 Carbon-Flora, i., p. 273. 



Sorodadus, Lesquereux (in part), Coal Flora, vol. i., p. 327. 



Description. — Fertile and barren pinnules dissimilar, the 

 fertile pinnules having the limb much reduced. Sporangia 

 exannulate, tapering to a point at the apex, contiguous, more 

 or less united among themselves, and suspended like a fringe 

 from the margin of the fertile pinnule. 



Remarhs. — This genus has been described and illustrated 

 by Zeiller in the Ann. d. Sc. Nat. (/. c.) and in his " Flore 

 foss. d. bassin houil. d. Valenciennes." In this latter work 

 he gives additional and fuller figures of Crossotheca Crepini, 

 Zeiller,^ the type of the genus, and also figures a second 

 species, Crossotheca Boulayiy Zeiller.^ 



The name of Sorotheca has been applied to the same plants 

 by Stur ; but his paper containing the description of his 

 genus did not appear till some months after the issue of that 

 in which Zeiller's genus Crossotheca was defined. 



Probably Sorodadus sagittatus, Lesqx.,^ is referable to 

 Crossotheca ; but Sorodadus, Lesquereux, has been employed 

 by him merely as a genus in which to place " fructifications 

 of ferns in separate branches and of unknown attribution " 

 without any attempt at a definition, and, in fact, it embraces 

 fructifications belonging to ferns of very different generic 

 affinity. 



The sporangia of Crossotheca are linear, the base being 

 slightly broader than the tapered apex. They are unprovided 

 with an annulus, and the walls are composed of cells elongated 



^ Loc. cit, p. 112, pi. xiii., figs. 1-3. 



2 Loc. cit., p. 115, pi. iv., fig. 4, 



3 Coal Flora, vol. i., p. 329, pi. xlviii., figs. 10 and 106 ; vol. iii., p. 762, 

 pi. C, figs. 4-5. 



