1 6 The Irish Naturalist. February' 



two of the most marked features of the more extreme 

 forms, their tripinnate division and the Hnear shape of the 

 ultimate divisions. 



Britten-'- gives two figures of the plant, one (p. loS), taken 

 from a specimen in the British Museum representing a 

 fine subquadripinnate form, the other (p. io6) no more 

 divided than his figure (p. 107) of the type. 



E. J. Lowe- says, " perhaps even a distinct species . . . 

 Outline pentangular, and in the larger fronds subquadri- 

 pinnate . . . The apices of the fronds and pinnae caudate 

 ... It differs from the normal species in being more sub- 

 divided, in its thinner and more papery texture, and in 

 the presence throughout of linear-acute erect segments and 

 teeth." His figure (repeated from his " Ferns, British and 

 Exotic," 5, 75, 1867) represents a subquadripinnate form 

 with long-ovate lobes. 



Bos well and Brown^ illustrate a fine quadripinnate form 

 with oblanceolate deeply toothed lobes — quite an extreme 

 form, though the ultimate divisions are not so linear as in 

 Newman's figure. In their description they emphasize the 

 satiny lustre of the " mostl}^ tripinnate or subquadripinnate" 

 fronds, the acuminate extremities, the " ultimate pinnules 

 or segments ascending-erect, longly wedge-shaped at the 

 base, very acute, serrate, with mucronate teeth longer than 

 broad." 



Babington's diagnosis* is " fronds much shorter than 

 the stipe triangular-prolonged, pinnae and pinnules 

 lanceolate-attenuate, ultimate subdivisions very acute." 

 This would admit as acutmn a good many plants other than 

 the extreme form. 



Christ^ says of A. Adiantum-nigrum — Very variable, from 

 smallish long-lanceolate forms, with broad segments to 

 broad-deltoid large forms with very much divided fronds 



1 " European Ferns," 106, 1879. 



- " Our Native Ferns," 2. 173, 1880. 



3 Sowerby's " English Botany." ed. iii.. 12, 123, pi. 1875, 1883-86. 



* " Manual of British Botany," ed. ix., 529, 1904. 



5 " Farnkrauter der Erde," 202, 1897, 



