BOTRYOPTERIDEAE 



503 



The spores are of approximately uniform size, and the plant appears to 

 have been homosporous. 



The sporangia of Botryopteris forcnsis have also been observed : 

 they are of smaller size, and have the broad annulus on one side only. 

 But in other respects they resemble those of Zygopteris. 



FIG. 272. 



Zygopteris, sp. i, group of four sporangia on a common pedicel (). X 10. 2, two 

 sporangia on pedicel. The upper shows the annulus (c) in surface view, with spores 

 exposed aty"; the lower in section. X 20. 2 l>is, sporangium cut in plane of annulus. 

 3, group of sporangia in transverse section. X20. Lettering common to the figures. 

 a, common peduncle; b, sporangia! wall; c, annulus; e, tapetum (?) ; f, spores; in, 

 pedicel of individual sporangium ; , probable place of dehiscence. All after Renault. 

 (From Scott's Studies in Fossil Botany.) 



A particularly interesting fructification attributed to this affinity is 

 that described as Corynepteris (Fig. 273). Hitherto it is known only 

 in the form of impressions. The leaves were of the Sphenopteroid, or 

 Pecopteroid type, and the pinnules bore each a single sorus, of five 

 to ten sporangia, grouped round a common centre. The annulus is 

 here again a broad lateral band, consisting of several cell-rows : as the 

 sporangia are grouped in the sorus the annulus of each sporangium is 

 in juxtaposition with that of its next neighbour, a condition not unlike 



