546 



FILICALES 



The sporangia of Mohria are radially constructed, the apex and base 

 being opposite (Fig. 302 D, E). In the other genera the sporangia are more 



or less curved, so as to be dorsiventral : 

 this curvature is slight in Aneimia and 

 Schizaea (Fig. 302 A, B, F, G), but very 

 marked in Lygodium (Fig. 302 c). 



Here it will be well to introduce 

 a brief notice of certain fossil sporangia 

 which have been referred to this affinity, 

 for they help to an understanding of 

 the structure of those of living forms. 

 The best known of these is Senften- 

 F, G- 3 o 3 . bergia (Pecopteris] elegans, Corda. from 



(Pecopteris) dfrw, Corda. the U PP Gr Carboniferous (Fig. 3 O 3 ) I it 



^=a small piece of sporophyii (*). 5=a spor- corresponds to Sckizctea both in the 



angium (- T ). (After Zeiller, from En^ler and .... 



Pranti, Nat. Pflansen/aitt.) disposition of the solitary sporangia 



and in their form and mode of dehi- 



scence ; but the annulus is composed of several cell-rows, and the terminal 

 " plate " has not been observed. Zeiller points out, however, that this is not 

 an absolute difference from living forms, for various species of Ly god in in 

 (a genus which has itself been traced back 

 to the Cretaceous Period), have a partially 

 double series of cells of the annulus, while 

 the " plate " in living forms is often so 

 small that a similar one in a fossil- 

 impression might well escape detection. 1 

 A second example is the genus Klukia, 

 the fructification of a Pecopterid from the 

 Jurassic, of which several species have 

 been described by Raciborski. 2 Here the 

 arrangement of the sporangia, their struc- 

 ture, and line of dehiscence are as in 

 Schizaea, there being only a single series 

 of cells of the annulus (Fig. 304). In 

 both of these genera of fossils it is to be FIG. 304. 



noted that the sporangia are intra-marginal, AVXV>_ ,-..// (Phiiipps). 



,- r i Fertile pinnule of last order, seen from 



on the lower surface of the pinnule, but be i ow ('y). From the Jurassic . 



without any indusial protection, while there 



is no specialisation of the fertile pinnules. 



From such comparisons it would appear probable not only that the 



Schizaeaceous type is an ancient one, but that it sprang from plants with 



a Pecopterid type of frond, without differentiation of specialised fertile 



pinnules, and that the sporangia were intra-marginal, on the lower surface. 



1 />'////. Sac. Bot. de France, T. xxiv., p. 217. 

 - EngleSs Ja/ir/i. , xiii., p. I, Tnf. I. 



