130 Proceedings of the Royal Physical Society. 



figs. 3 and 4. The capsules or urceolate indusiums are oval 

 in form, and show a small depression at their apex, which 

 probably indicates the position of an aperture (figs. 5 

 and 6). Their greatest length measures 2V of an inch. 

 They are arranged in two rows, one on each side of the rachis 

 of the pinnule, the capsules being alternate, as shown in figs. 

 4 and 6 ; but they commonly appear as secund, the one row 

 being bent over the other. This is well shown in fig. 3. 



The different positions of the capsules are probably 

 dependent upon their state of ripeness when fossilisation took 

 place. From the fine state in which the specimens are pre- 

 served, the outline of the cells composing the capsules is 

 distinctly shown. 



The affinities of this fern to recent genera are somewhat 

 obscure. The capsules in form resemble those of Hymeno- 

 stachys (Hymenophyllaceae) ; but in the fossils there is no 

 discernible trace of a column, which forms a constant character 

 in that genus. They agree, however, in the dimorphic con- 

 dition of the fronds. I fear that at present we can only pre- 

 sume that this fern is most probably referable to the Hymeno- 

 phyllaceae. Both fertile and barren fronds are plentiful in the 

 Coal Measures, Sauchie, near Alloa ; and a fine barren speci- 

 men is exhibited in the Museum of the Glasgow University, 

 from the " Eoof of the Kiltongue Coal, Bailieston." 



I have placed this fern in Schimper's Eusphenopteris in 

 preference to Brongniart's generic name of Splunopteris, as 

 those individuals with cuneate segments form a very dis- 

 tinct group of the Sphenopteroids, and their removal from 

 Sphenopteris helps to simplify that complex genus.* 



In some recent works on vegetable palaeontology attempts 

 have been made to found a classification of ferns on the basis 

 of their fructification ; but so few fossil ferns having been 

 obtained in this state has necessitated the introduction of two 

 sets of characters in the classification of one group of plants : 

 viz., those found in fruit are classified according to the structure 

 and arrangement of that organ ; but those whose fruit is still 

 unknown, are classified, as formerly, from characters possessed 

 by the barren fronds. 



* Schimpcr und Zittcl, " Haiulhiicli dor Palioonlologio," ]i. 107. 



