68 BRITISH FERNS. 



circumstances which render them dwarf, or more or less 

 spreading and drooping when in situations which are fa- 

 vourable to enlarged development : in the former case the 

 fronds are thicker and more leathery in texture ; in the 

 latter, thinner and less rigid, from being produced in very 

 damp shady situations. The usual form of the fronds is 

 what is called strap-shaped, that is, narrow oblong-lanceo- 

 late, much elongated ; they taper towards, and are acute at, 

 the apex, narrowing a little downwards, and becoming cor- 

 date at the base; the margin is entire, or very slightly 

 wavy, and they are supported on shaggy stipes averaging 

 about a third of their entire length. The fronds have a 

 strong midrib or costa, extending throughout their whole 

 length, from which are produced forked veins, the branches 

 of which (venules) lie parallel, and proceed direct towards 

 the margin, terminating just within the edge in a club- 

 shaped apex. The sori, which are oblong patches of un- 

 equal length, lying in the direction of the veins at short in- 

 tervals along the upper two-thirds of the length of the 

 frond, are each composed of two proximate lines of fructifi- 

 cation laterally united ; each line, however, consisting of a 

 complete sorus, so that the two united are properly called a 

 twin sorus. The indusia which cover these, have their at- 

 tachment on the upper and lower sides of their respective 

 venules, the other edges overlapping one the other. 



This is the ordinary form of Scolopendrium ; but there are 

 a great number of very curious and some very distinct 

 varieties, differing only, however, in the form of the frond.", 

 and not in the fructification, where it is present. These 

 varieties, which are noticed at length in our Handbook of 

 British Ferns, are for the most part perfectly constant under 

 cultivation, although they have, no doubt, originated in 

 aberrations that is to say, accidental variations, from the 

 original species, which have been perpetuated naturally or 

 by art. It is moreover a curious fact, that most of them are 

 reproduced from spores. 



The variety crispum is one of the most beautiful of them ; 

 in this, the same outline of frond prevailing, the leafy por- 

 tion is so much more developed than the midrib, that the 

 margin becomes excessively undulated, giving the fronds a 

 very elegant curled or crisped appearar.ce. This sort is 

 barren. 



The variety polyscliides is very curious and distinct. The 

 fronds of this are linear, and blunt at the apex, much nar- 

 roTvfr than in the common sort, and the margin is deeply 



