124 ENGLISH BOTANY. 



bipinnate ; ultimate pinnules or segments ascending-erect, longly 

 wedgeshaped at the base, very acute, serrate, with mucronate teeth 

 longer than broad. 



On rocks, walls, and banks. Vars. a and /3 not very abundant, but 

 generally distributed, extending north to Orkney and Shetland. 

 Frequent throughout Ireland. 



Yar. y. Serpentina on serpentine rocks, at Cabrach, in Aberdeen- 

 shire, on the confines of Banffshire, where it was discovered by the 

 Rev. Andrew Christie. To this var. I am inclined to refer also a 

 plant sent me by Mr. G. H. Kinahan, labelled " On serpentine 

 a little south-west of Glendalough Hotel, Connemara." 



Yar. y. acutum appears to be confined to the south-west of Ireland. 

 I have specimens from Glen Carragh, Mr. G. Maw ; Killarney, Mr. 

 E. T. Bennett ; and Bandon Hill, near Peafield, Eev. J. Allen. Mr. 

 G. H. Kinahan writes to me that it is frequent in Connemara, Galway, 

 and S.W. Mayo, but I have not seen specimens. Mr. H. C. 

 Watson reports it from Surrey, and Dr. Lowe from Norfolk. Besides 

 these localities it is reported from Jersey ; from Combe Royal, south 

 Devon ; and the walls of the cathedral of St. Asaph, Wales ; but as I 

 have not seen specimens from these places, I do not know if they 

 belong to acutum, as I understand it, or are merely finely divided 

 states of var. a. 



England, Scotland, Ireland. Perennial. Summer, Autumn. 



A very variable plant, which Milde and others divide into 3 sub- 

 species, and certainly taking the typical forms of each of these one 

 is much inclined to endorse their opinion ; but these principal forms 

 are so intimately connected by intermediates, and the characters 

 become so crossed, that I have found myself compelled to agree with 

 those writers who regard them all as forms of one species. It is not, 

 as in the case of the Lastreas, that we have distinct forms of which 

 there are abundant individuals connected by intermediate forms of 

 which there are few individuals : the types of the distinct forms of 

 Lastrea are abundant, the intermediates scarce, and each inter- 

 mediate form occurs only where the two typical forms which it connects 

 grow together. 



Yery different from this is the case of Asplenium Adiantum-nigrum, 

 in which there are far more individuals of the connecting forms than 

 of the type-forms of two out of the three possible subspecies, at least 

 in Britain and central Europe ; while in the south of Europe and the 

 Canary Isles another type-form becomes prevalent, and the inter- 

 mediates which connect it with the form most common in Britain are 

 more abundant than the northern form. 



