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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 12, 



It belonged evidently to a very delicate and pretty Fern, very like 

 some of the more finely-cut Dicksonice of the present day ; and its 

 fructification clearly shows that its real affinity was with that genus. 

 The fragment is bipinnatifid : its rachis rather broadly bordered ; 

 the leaflets (pinnulse) alternate, somewhat oblong in outline, regularly 

 pinnatifid, with a strongly marked, wavy or slightly zigzag midrib ; 

 their segments separated a little more than half-way to the midrib, 

 alternate, or in part nearly opposite, short, contracted below, dilated 

 at their apices into the indusia containing the fructification, which 

 are convex, with a rounded or rather reniform outline, their greatest 

 diameter being transverse. No capsules are visible, the fructification 

 being probably in a young state. In general, each segment is 

 traversed by a single vein, and bears a single indusium, but a few of 

 them are slightly two-lobed, bearing two indusia, and having their 

 vein forked. The barren segments, of which only one is seen in this 

 specimen, are fan-shaped, unequally and rather deeply toothed at the 

 apex, with obtuse teeth ; the veins radiating, without any midrib. 



The indusium, which is all that we see of the fructification of this 

 interesting little Fern, closely resembles in form and position the in- 

 dusia of certain species of Dicksonia, of the Cidcita group, especially 

 D. coniifolia (Hooker)*. In these plants the indusium consists of 

 two convex, reniform, equal or nearly equal valves, terminating the 

 short lateral lobes or teeth of the leaflets. To show their similarity 

 to our fossil Sphenopteris, I have drawn ( PI. XII. fig. 2) a leaflet 

 of a recent Dicksonia (I believe, D. coniifolia), from New Granada f ; 

 whereby it will be seen that the indusium of the fossil so well agrees 

 with that of the recent plant, in an immature state, as to leave little 

 doubt that both belonged to the same genus. The species is, how- 

 ever, clearly different, the segments of the recent Dicksonia, when 

 barren, being elongated and acute, the leaflets themselves longer and 

 more taper-pointed, and the rachis on which they are set having a 

 very narrow border ; besides that the frond is of a more rigid aspect. 

 It is only with this group or section of Dicksonia that our fossil can 

 well be compared : in most of the other species, and particularly in 

 those composing the subgenus Patania%, the indusium is more cup- 

 shaped, and opens towards the back of the leaf, not in the plane of 

 its margin, as it does in D. Cidcita, coniifolia, and Martiana ; it is 

 moreover, in the greater number, seated in the sinuses of the lobes or 

 teeth, and not at their tips. 



Of the numerous fossil Ferns included in the genus Sphenopteris 

 of Brongniart, very few have been found with distinct traces of fruc- 

 tification ; and I am not aware that any in this state, from the oolitic 

 formations, have yet been published. Of those described and figured 

 by Goeppert, which are all from the coal-formation, his Hymeno- 

 phyllites Humboldtii% perhaps comes nearest to the present plant, 

 but is yet abundantly different. The form of the indusia in that 



* Species Filicum, vol. i. p. 70, t. 24 A. 

 f No. 1009 of Linden's collection. 

 + See Hooker's Spec. Fil. vol. i. tab. 26-28. 

 § Syst. Fil. Foss. p. 254. t. 31. f. 1, 2. 



