FILICES. 155 



the present state of our knowledge be regarded as premature. Stur has 

 included a large number of Sphenopteridae in his genus Calymmotheca ; 

 these all agree in the circumstance that their fertile leaf-segments terminate 

 in peculiar capsule-like indusia formed of several lobes, which close upon 

 one another like valves and ultimately expand and assume the form of a star 

 or almost of a corolla. These indusia show a remarkable variety of dimen- 

 sions, and in some species from the Culm especially they reach a very con- 

 siderable size. The details of their form also vary much ; the valves on the 

 median line of the dorsal surface in Calymmotheca Stangeri, Stur, are covered 

 with thorn-like projections. Stur has done well to bring genera like Sphae- 

 ropteris, Wall, and Diacalpe, Bl. from among recent Ferns into comparison 

 with Calymmotheca, and Cyathea Brunonis, Wall, might be added to them ; 

 if the laminae of the leaves disappear from Sphaeropteris barbata, Wall., 

 and the nerves only are left with the thick-walled stalked sori, a form like 

 Calymmotheca would in fact be produced. But this comparison, serviceable 

 as it is in some respects, tells us nothing about the affinity of our forms, nor 

 shall we be able to determine that point until we succeed in discovering the 

 altogether unknown sporangia. Stur himself, who inclines to place them 

 with Cyatheaceae, fully recognises the precarious nature of this disposition. 

 From Calymmotheca Stur next proceeds to the consideration of his genus 

 Sorotheca, in which the fruiting terminal pinnae are flattened out and 

 thickened, and are encircled with numerous narrowly lanceolate indusial 

 valves. The points of insertion of the sporangia can be seen as small scars 

 on the surface of the pinnae. At first the valves of the indusium are con- 

 nivent, but they subsequently expand in a stellate manner. Zeiller l indeed, 

 who has described the same plant from the Belgian coal-fields as Crosso- 

 theca Crepini, explains the parts of the fructification in a totally different 

 manner, since he takes the lanceolate projections, Stur's indusial valves, for 

 the sporangia themselves. In that case the scars observed by Stur, which 

 Zeiller 2 in his rejoinder to Stur rather passes over, would not be easy to 

 understand. Lesquereux ;5 has figured some fructifications which look like 

 these of Sorotheca, but whether they should be placed with that genus or 

 with Calymmotheca is a point which cannot be determined from the some- 

 what imperfect account given of them. The American author has named 

 these objects Staphylopteris, Lesq. (S. Wortheni, S. asteroides, S. stellata), 

 but he also includes in his genus various other forms, such as S. sagittatus, 

 Lesq., which evidently have nothing whatever to do with it, as has been 

 already pointed out by Schimper 4 . 



The doubts, which are shared by Stur himself, as was before said, 

 respecting the relationship of the genera Calymmotheca and Sorotheca to 



1 Zeiller (7). 2 Zeiller (6). 3 Lesquereux (3), vol. iv, p. 405; t. 14, and (4), p. 310; 



1. 2, f. 2. * Schimper (1), vol. iii, p. 513. 



