SOME FERNS FROM THE CARBONIFEROUS FORMATION. 149 



portion of the frond confined to the lower secondary pinnae, where the fertile 

 pinnules bear 1-3 pedicellate indusia at the extremities of the excurrent veins. 

 In the earlier condition the indusia are oval, but at maturity split into four 

 valves. 



Remarks. — From the figure of this species given by Dr Stur in his Carbon 

 Flora, the fronds of this fern must have attained to large dimensions. The 

 form of the tertiary pinnae varies much on the upper and lower parts of the 

 fern ; on the upper portion they are small, about 3 mm. long, 2 mm. broad, and 

 more or less oval in outline ; those towards the apex of the secondary pinnae 

 are more or less united among themselves. On the lower secondary pinnae the 

 tertiary pinnae are 15-20 mm. or more long, and bear many pairs of alternate 

 pinnules, which are usually united to each other for ^ or § of their length. The 

 free portion is triangular, and has a well-defined central and usually two 

 lateral veins, one given off from each side of the medial nerve. The fertile 

 pinnules do not differ in form from the barren, except in the veins being pro- 

 duced to form little pedicels to which the oval indusia are attached (PI. VIII. 

 figs. 9, 10). Occasionally only the upper pinnules are fertile, but quite as 

 frequently the lower, as well as the upper pinnules bear fruit. 



The fruit of this fern, as pointed out by Dr Stur,'" is composed of four 

 valves. This four-cleft appearance, however, is only shown when the indusium 

 has reached maturity and split for the dissemination of the spores ; in the 

 young state the indusia are oval as seen at PI. VIII. fig. 9. As to the manner 

 in which the spores are arranged within the indusium nothing is known. 



Description of Specimen. — PI. VIII. fig. 8. The example figured is the 

 only British specimen of this species with which I have yet met. It shows a 

 portion of a secondary pinnae, bearing the remains of twelve tertiary pinnae, 

 none of which are very complete, but all are fertile, except the two upper 

 pairs. The fertile pinnules bear in some cases three (fig. 10) and in others 

 only one indusium (fig. 9). 



At fig. 9 is exhibited the young, and at fig. 10 the more advanced con- 

 dition of the indusia, where they have split into valves. 



This specimen was in the collection of the late Mr Henry Johnson, F.G.S., 

 Dudley, from whom I received it for examination. 



Horizon. — Middle Coal Measures. 



Locality. — Corseley, near Dudley. 



* Carbon Flora, fyc, p. 254. 



