XXl] MATONINEAE 361 



Lacoopteris Dwnkeri (Schenk)^. 



This species is represented in several Wealden localities by 

 fragments of fertile pinnae similar to those of L, polypodioides. 

 It is almost impossible to distinguish small specimens of the 

 Wealden fern from Heer's genus Naihorstia (Marattiaceae) 

 unless the sori are well preserved. This species occurs in 

 Wealden beds in England, Germany, Belgium, and elsewhere 

 and has been discovered by Dr Marcus Gunn in Upper Jurassic 

 plant-beds of Sutherlandshire (N.E. Scotland). 



Laccopteris is widely spread in Rhaetic, Jurassic and Lower 

 Cretaceous floras. It affords evidence of the former abundance 

 in northern latitudes of a family now represented by the two 

 species of Matonia confined to a restricted area in the southern 

 hemisphere. 



Matonidium. 



Schenk^ instituted this convenient term for fossil fern fronds 

 agreeing in habit and in their sori with Matonia pectinata (figs. 

 227, 228, p. 292). Zeiller^ has drawn attention to the fact that 

 the Mesozoic species differ from the surviving types in the 

 greater number of sporangia in each sorus, and, it may be added, 

 in Matonidium the fertile pinnules are more richly supplied with 

 sori than are those of Matonia. Unfortunately our knowledge 

 of the structure of the sporangia of Matonidium is less complete 

 than in the case of Laccopteris, but such evidence as is available 

 justifies the conclusion that Matonia is a direct descendant of 

 ferns which formed a prominent feature in European Jurassic 

 and Wealden floras. It is interesting to find that in a Cretaceous 

 species, described by Krasser (fig. 265, A) since the publication 

 of Zeiller's paper, the sori appear to be identical in distribution 

 and in appearance with those of the recent species. 



I am indebted to Prof. Bommer for permission to reproduce 

 the unpublished drawing represented in fig. 237 D (p. 310) of a 

 section of the rhizome of Matonidium from the Belgian Wealden 



' See Seward (94') A. and (00) for an account of this fern. 

 = Schenk (71) p. 219. ^ Zeiller (85). 



