382 GENERA OF FERNS. 
of a genus, I cannot make it even distinct from the Mer- 
tensia dichotoma of Willdenow. 
Div. III. Scaizawacem. Mart. 
Sporangia oval, oblong, rarely globose, sessile, apex 
striated, rayed, opening lengthways (vertically) on their 
exterior side, produced on contracted marginal lobules, or 
special appendices, in the form of simple, or racemose, or 
paniculate, contracted fronds or spikelets. 
Obs. The oval sporangia, furnished with a striated apex, 
analogous to a transverse ring, readily distinguish ScAi- 
zeacee from either of the preceding divisions. The nearest 
relationship is with Osmundacee, to which the species 
were formerly annexed ; but Osmundacee, as now restricted, 
differs in habit and in the structure of the sporangia. The 
number of species forming Schizeacee amounts to about 
forty, and these have been hitherto comprehended under 
four genera, which, with the exception of a few species, 
agree in having free, direct, venation; one species of 
Lygodium and a few species of Anemia exhibiting anastomose 
veins. Although these few species do not possess any 
peculiarity in habit, still I have deemed it necessary, in order 
conspicuously to mark their difference in venation, to arrange 
them under two separate genera. 
129. Lycopium, Sw. 
(Hydroglossum, Willd. Ugena, Cav.) 
Veins free. Fertile appendices marginal, forming numerous 
linear spicule, composed of two rows of indusiate imbricate 
cysts, each cyst containing an oval sporangium, which is 
attached by its interior side, and resupinate. 
Rhizoma cespitose. Fronds twining, scandent. Pinne 
conjugate, lobed, palmate, pinnatifid, or pinnate ; the segments 
sometimes entirely contracted, forming a dense sporangiferous 
