124 W. WALTER WATTS. 



is a continuation of the lateral growth of the original fer- 

 tile leaf; the indusium is said to have made a "phyletic 

 slide" in the process of development. 



The bearing of Dr. Bower's investigations upon Blechnum 

 capense lies in this: that this fern is of such variable form 

 that it exhibits the characters, now of Lomaria, and now 

 of Eublechnum. Generally, the variabilty takes such 

 partial forms as the following: a pinna may show the 

 normal sterile spread in its lower half, and, in its upper 

 half, the narrow linear fructification; or, vice versa, the 

 upper part of the pinna may have the normal sterile spread, 

 and the lower part the narrow lomarioid fructification; or, 

 again, the pinnae on one side of a frond may be of the usual 

 sterile form, and those on the opposite side may show the 

 narrowed fertile character. But Dr. Bower, with a wide 

 range of specimens before him, goes further, and says that 

 "types are sometimes found in which the pinna appears as 

 in B. brasiliense, with the linear sori close right and left of 

 the midrib, and the flange, which is usually small in this 

 species, widened out into a broad expansion with an exten- 

 sive venation of its own" (p. 381 k>c. cit.). 



So far as our Australian specimens are concerned, the 

 great majority of them show the normal lomarioid fruiting 

 form, i.e., exhibit typical dimorphic characters; but, in the 

 Sydney Herbarium, there are specimens that show an 

 undoubted eublechnoid tendency. This tendency, for the 

 most part, appears in the irregular forms indicated by Dr. 

 Bower, — forms in which the lomarioid fructification shares 

 a frond with the eublechnoid sterile formation; but, now 

 and again, specimens are found that exhibit the eublechnoid 

 character, more or less, throughout, though, where this 

 occurs, the fertile frond is usually much narrower 

 than the sterile: thus preserving the typical dimorphic 

 character. 



