1023 



vence from established genera in the structure of some important organ 

 or system of organs. Now the vascular system must be regarded as 

 of the highest importance in the vegetable economy even in reference 

 to propagation, it being not at all infrequent to meet with extraordi- 

 nary means of development in connexion with it, viz. adventitious 

 buds ; and in ferns particularly those points of the veins which serve 

 in normal cases as the receptacles to which the sori are attached, in 

 other cases become viviparous and develope gemmae from which new 

 plants are produced. He believes, moreover, that characters derived 

 from this system of vessels, when taken in connexion with the fructi- 

 fication, though sometimes forming groups of considerable extent, and 

 occasionally separating species having some external similarity, never- 

 theless in no case bring together obviously ill-assorted species, but 

 rather associate those of obvious similarity and aflSnity. 



For these reasons he is not prepared to follow Sir W. Hooker in 

 setting aside the genus Hewardia of Mr. John Smith. He regards the 

 difference as broad and important between the accidental anastomos- 

 ing of contiguous venules which occurs in some species of Adiantum, 

 and a constant and complete reticulation, such as exists in the genus 

 Hewardia ; and he concludes that that genus should be retained. 

 This conclusion he finds unexpectedly confirmed in Fee's ' Genera 

 Filicum,' just received iu this country, where the same view is taken 

 of the species of Hewardia as that which he had previously adopted, 

 and an additional species (H. serrata) mentioned, of which he had no 

 previous knowledge. 



The species enumerated by the author are arranged as follows : — 



* Sori continui ; venae primariae costiformes. 



1. Hewardia adiantoides, J. !Smilh = Adiantum Hewardia, Kunze. 



2. H. dolosa, Fee = Ad. dolosum, Kunze. 



** Sori interrupt! ; venae uniformes. 



3. H. Le Prieurei, Fee = Ad. Le Prieurei, Hook. 



4. H. serrata, Fee. 



Mr. Moore regards H. Wilsoni, F^e (Adiantum, Hook.), as a true 

 Adiantum ; as also Sir W. Hooker's variety y. of Ad. lucidum. In 

 both these the dichotomous veins occasionally anastomose ; but there 

 is nothing like complete reticulation, and the union, when it does 

 occui", is evidently accidental. 



If the name Hewardia be retained, as the author proposes, for the 



