22 Mr. R. Kidston on the 



III. — On the Fructification of two Coal-measure Ferns. 

 By Robert Kidston, F.E.S.E., F.G.S * 



[Plate I.] 



Ceossotheca, Zeiller, 1883. 



Crossotheca, Zeiller, Ann. d. Sc. Nat, Of s4r. Bot. vol. xvi. p. 180 ; id. 



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

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



id. Carbon-Flora, i. p. 273. 

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



Description. — Fertile and bm-ren 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. 



Remarks. — This genus has been described and illustrated . 

 by Zeiller in the Ann. d. Sc, Nat. {I. c.) and in his ^Flore foss. 

 d. bassin houil. d. Valenciennes.' In this latter work he gives 

 additional and fuller figures of Crossotheca Crepinij Zeiller f, 

 the type of the genus, and also figures a second species, 

 Crossotheca Boulayi, 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 So7-ocladus sagittatus, Lesqx. §, is referable to 

 Crossotheca ; but Sorocladus^ 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 elon- 

 gated in the direction of their axis. The sporangia are 

 placed close together, and it is difficult to determine whether 

 they are free or united to each other. According to Zeiller 



* Communicated by the Author, having been read before the Royal 

 Physical Society of Edinburgh, April 18, 1888. 



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



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



§ Coal Flora, vol. i. p. 329, pi. xlviii. figs. 10 and 10 h, vol. iii. p. 762, 

 pi. C. figs. 4-5. 



