MATONIDIUM. 65 



cut 20, p. 207 of Phillips' " Geology of Yorkshire " and Schenk, 

 pi. xxviii. Palaeontographica, xix. 



Trautschold figures from the Klin Sandstone several pieces of 

 fronds which undoubtedly come very near the Wealden species. 



His figures of Pecopteris Althausii, Dunk., agree with Schenk's 

 of the North German plant, except in a slight difference in 

 size. 



Possibly Pecopteris explanata, Traut., should be kept as a 

 distinct species, but this should be referred to Matonidium-, as 

 regards habit this plant is very close to Velenovsky's fig. 3, pi. ii. 

 of Microdictyon Dunkeri (Schenk). 1 Another Russian species, 

 Pecopteris pachycarpa, Traut., 2 should also be removed to Schenk's 

 genus, but probably its straighter and less falcate pinnules justify 

 a distinct specific name. 



Schenk's later figures of the species throw further light on the 

 character of this fern, and show, amongst other things, that the 

 shape of the pinnules varies considerably in different specimens. 

 The same variation in the size and form of the ultimate segments 

 is shown in Heer's figures of this species from Portugal ; possibly 

 some of his specimens should be referred to another species, but it 

 is very difficult to decide what limits to attach to the variation in 

 size in a single species. 



In discussing the position of this species, Schenk notes the 

 close correspondence of the sori and the individual sporangia with 

 the Cyatheacea type, and this similarity as regards the fertile 

 segments is confirmed by the apparently identical habit of the 

 frond of Matonia pectinata, Br. The sori of the recent species 

 are more circular in form than in Matonidium Gopperti, where they 

 appear to be elliptical ; compare e.g. Hooker and Baker, 3 pi. i. 

 fig. 8, and Schenk, Palaeontographica, xix. pi. xxviii. pi. xxviii. 

 figs. 2 and 2a. 



V. 2218. Woodcut, Fig. 7. 



Portions of several pinna? having to some extent the characters 

 of Cladophlebis Browniana (Dunk.), but the form of the fructifica- 

 tion and the position of the detached pieces on the matrix show 



1 Abh. k. bohm. Ges. Wiss. vii. folge, vol. ii. 1888. 



2 Trautschold, loc. cit. p. 30, pi. xix. tigs. 6a and b. 



3 Synopsis Filicum, 1868. 



