ASPIDTUM DTLATATUM. 79 



Africa^ in the Azores; in America, at Sitka, Port Mulgrave, 

 Canada, and the Rocky Mountains. 



The ordinary form is ovate-lanceolate; bipinnate to tripinnate. 

 Pinnae opposite, numerous, the basal pair obliquely triangular- 

 elongate; the posterior pinnules considerably larger than the 

 anterior pinnules. The pinnae taper gradually from the base 

 to the apex. Pinnules ovate-oblong, rather acute, the basal 

 ones stalked, and the upper pinnules sessile and decurrent, 

 the lovrer ones deeply pinnatifid, occasionally pinnate. The 

 divisions are all sharply dentate, ending in a bristle-like 

 point. 



Veins forked. 



Caudex stout, mostly upright; crown densely scaly. 



Stipes terminal, from a third to half the length of the 

 frond; densely scaly. 



Pructification occupying the whole of the under side of the 

 frond. Sori numerous, circular, and indusiate. Indusium 

 reniform and membranous. 



Length from two to six feet, usual size from two to three 

 feet; breadth from six to sixteen inches. Colour dark green 

 above, paler beneath. 



One of the most difficult species to understand, as in its 

 different forms it approaches both A. fcenisecii and A. spinu- 

 losum; from the latter it is known by A. spinulosum having 

 a creeping caudex, the few broad pallid scales of its stipes, and 

 by the indusium being entire. 



The form TajiacetifoUum, or ^'Tansy-leaved prickly-toothed 

 Buckler Pern," is tripinnate, with broad fronds; stipes having 

 numerous entire dark brown scales, with a darker bar down 

 the centre; lanceolate in form. 



The form Nanum, or "Dwarf prickly-toothed Buckler Pern," 

 from Settle and Ilfracombe, is always dwarf, varying from two to 

 ten inches in length. 



The form Dumetorum, or "Thicket prickly-toothed Buckler 

 Pern," is also dwarf, with broad frond, having large abundant 

 fructification, and is remarkable for the glandular surface of 

 the fronds. 



The form Collinum, the "Hill prickly-toothed Buckler Pern," 

 known also as "Pinder's Pern," has the pinnae distant and 

 spreading. 



