94 ALLOSORTJS CRISPUS. 



is very handsome, the barren and fertile fronds contrasting 

 greatlv with each other. 



A hardy, deciduous, indigenous species. 



A local yet abundant Fern on the Scotch mountains; and 

 hills in the North of England. In Ireland it is rare, and 

 only occurs in Antrim, Down, and Louth. In North "Wales, 

 according to Mr. Moore, it is not found below an elevation of 

 four hundred and fifty feet, and in Scotland it ascends to 

 three thousand four hundred and fifty feet. In Lancashire, it 

 descends to nearly the sea level. 



It is widely spread through Europe, occurring in Lapland, 

 Norway, Sweden, Denmark, Germany, Hungary, Switzerland, 

 France, Spain, Italy, Sitka, England, Scotland, Ireland, and 

 Wales. 



The Allosorus crispus does not succeed well unless it is 

 allowed abundance of drainage, as an excess of moisture is 

 almost certain destruction. 



Sterile fronds leafy, generally about equal in length with 

 the stipes, smooth, bipinnate, and sometimes tripinnate; pinnae 

 triangular-ovate in form, alternate, smaller as the apex of the 

 frond is approached; pinnules also alternate, ovate in form, 

 pinnate or pinnatifid, the lobes cut into linear acute teeth. 



Fertile fronds contracted, mostly only half as long as the 

 stipes, tripinnate, and occasionally quadripinnate in the lower 

 portion of the lowest pinna?; pinnae alternate, ovate in form, 

 pinnules alternate, pinnate above, pinnato-pinnatifid in the low- 

 est pinnae. The ultimate divisions are linear-oblong, obtuse, 

 and pctiolatc. Venation of the barren frond extending in a thin 

 vein along each pinnule, and branching off into each lobe; it 

 is simple except where the segment is bifid, then forked. In 

 the fertile fronds the vein runs in a sinuous course to the 

 apex of each ultimate division; usually simple, occasionally 

 forked, extending almost to the margin, and bearing a sorus 

 near to the extremity. 



The fructification generally occupying the whole under sur- 

 face of the frond; sori small and rounded, approximate, and 

 ultimately confluent, thus forming a continuous line. 



The margin of the pinnulets, though unaltered in texture, 

 are incurved over the sori. There is no indusium; spore-cases 

 stalked; spores smooth, roundish oblong. 



