530 PTERIDOSPERMS, ETC. [f!H. 



members of widely different families possessing pinnules of the 

 same general type, such as is represented in some recent species 

 of Davallia, Asplenium, and other ferns. 



The fronds of Sphenopteris may be bipinnate, tripinnate, or quadri- 

 pinnate ; the rachis may be dichotomously branched or the branching may 

 be of the pinnate type characteristic of most recent ferns. The pinnules 

 are small ; they vary considerably in shape even in a single frond, but the 

 chief characteristics are : the lobed lamina, contracted and often wedge- 

 shaped at the base (fig. 352), the dichotomously branched veins radiating 

 from the base or given off from a median rib at an acute angle. The 

 lamina may be divided into a few bluntly rounded lobes (fig. 352, C) or 

 deeply dissected into linear or cuneate segments (fig. 352, A, B, E). 



Examples of Sphenopteroid leaves have already been 

 described under the genera Coniopteris, Onychiopsis, Ruffordia, 

 etc. Among the numerous examples of Sphenopteris species 

 from the Carboniferous rocks mention may be made of Spheno- 

 pteris obtusiloha Brogn.^(fig. 352, A — C), which occurs in the 

 Middle and Lower Coal-Measures of Britain 2. This type is 

 characterised by the almost orbicular, oval or triangular pinnules 

 which may reach a length of 15 mm.; they are occasionally 

 entire, but more usually divided into 3 to 5 rounded lobes. The 

 forked veins radiate from the base of the pinnule. The rachis 

 may be dichotomously branched. Fructification unknown. 



The species S.furcata Brongn.^, characteristic of the Middle 

 and Lower Coal-Measures of Britain (fig. 352, E), is referred 

 to under Stur's genus Diplotmema* in which it is included 

 by some authors solely because of the dichotomous habit of 

 branching of the pinnae. 



The pinna represented in fig. 353 illustrates a similar type 

 of pinnule. This species, which is very common in the Calciferous 

 Sandstone of Scotland, was described by Lindley and Hutton 

 as Sphenopteris affinis^. 



The fronds of Sphenopteris affinis were discovered by 

 Mr Peach® in a fertile condition, but he regarded the reproductive 

 organs as those of a plant parasitic on the Sphenopteris fronds. 



1 For synonymy, see Kldaton (86) p. 68. 2 Kidston (94) p. 298. 



=* Zeiller (88) A. p. 147, Pis. iv. v. ; Kidston (86) p. 80. ■» See p. 535. 



5 Lindley and Hutton (31) A. PI. xlv. I' Peach (78). 



