45o STUDIES IN FOSSIL BOTANY 



Seward's Rachiopteris Williamsoni, which appears to be 

 the petiole of some other species of Sutcliffia. 



The vascular system of Sutcliffia has no parallel 

 among any plants at present known, though a remote 

 analogy may be traced with the anomalous structure 

 of certain lianes belonging to the Sapindaceae. The 

 genus is referred to the Medulloseae on account of the 

 general organisation of the leaf-base and petiole, the 

 numerous leaf-trace bundles, the tendency to dialystely 

 shown in the formation of the subsidiary steles, and the 

 histology of the vascular and cortical tissues. 



The stem, however, has not deviated far from the 

 monostelic condition, for the single central cylinder 

 forms the dominant feature of the vascular system, 

 while the meristeles serve to effect the transition to the 

 leaf-traces. The plant is of considerable interest, as 

 indicating the probable derivation of the Medullosean 

 stem from a simple protostelic type, -such as exists in 

 Heterangium among the Lyginodendreae. 



Fructification of Medulloseae. — There is one 

 case in which we have clear and direct proof that a 

 member of the Medulloseae, or, as we shoujd rather say, 

 of the Neuropterideae, was a seed-bearing plant. In 

 the same year in which the see^d of Lyginodendron was 

 first identified, Mr. Kidston was able to demonstrate 

 the presence of seeds in a species of Neuropteris, one of 

 the genera which Stur, twenty years before, had pro- 

 posed to exclude from the Ferns. 



In the well-known species N. heteropkylla, the frond 

 of which is illustrated in Fig. 161 (p. 426), bodies of 

 about the size of a hazel-nut, but relatively longer, were 



