176 



LYCOPODIALES 



[CH. 



megaspores occur in the lower sporangia, The megaspores, 

 having a mean diameter of 0'8 mm. "quite 40 times the size of the 

 microspores^" are characterised by tubular capitate appendages, 

 and by a conspicuous three-lobed projection (fig. 191, E)^ which, 

 as Scott suggests, may represent the outer spore-wall which 

 has split as the result of germination. It is not im- 

 probable, as shown in fig. 191, I, that this cap was present 



Fio. 186. A, B. Lepidodendron Veltheimianum. (Botany School, Cambridge.) 

 C. Lepidodendron macrophyllum. (British Museum. No. 377.) 

 X, Primary xylem ; x-, secondary xylem ; s, Stigmarian rootlet. 



before germination. The megaspores represented in fig. 191, 1, 

 illustrate their characteristic form as seen in a section 

 of a megasporangium, Sm ; the open beak-like portion of the 

 larger spore is probably the apical region which has split along 

 the three-rayed lines. These lines form a characteristic feature of 



1 Scott (00) p. 173. 



2 Scott [(08) p. 187] suggests that the projection may have formed a passage 

 for the admission of the microspores, or of the spermatozoids which they produced. 



