58 103. SELACUNELLA. 



in the axils of the higher fork branches, either tetrastichous and often 

 sharply square, or platystichous on the same plan as the leaves, but 

 then mostly resupinate (i. e. with the smaller sporophylla on the same 

 plane as the larger leaves, and vice versa); sporangia of 2 kinds, macro- 

 ' sporangia and microsporangia, placed singly in the axils of the sporophylla, 

 mostly monocious, rarely diocious, 1-locular, 2-valved; macrospores rather 

 large, subglobose, 1 4 in a macrosporangium, the basal side rounded, 

 smooth, verruculose, aculeate, rugulose or reticulate, the apical side 

 generally trigono-pyramidal and furnished with 3 ribs radiating from the 

 summit, rarely flattened and without ribs; microspores similar but very 

 minute, dust-like, very numerous in a microsporangium. Engl. & Prantl, 

 Nat. Pfl.Fam., I 4 , fig. 401408. 

 Cosmopolitan. 



103. SELA.OIlVEL.Lu^, Spring. 



Characters those of the family. 



Arrangement of the subgenera, sections and groups ('). 



A. HETEROPHYLLU11 (Subselaginella). Leaves very hetero- 

 morphous at least in the branched portion of the shoots, the branches 

 therefore conspicuously dorsiventral. 



which is often gradually decoloured from the midrib towards the margin. In order 

 to ascertain in dry material the presence of sclerotic cells, it is necessary to boil the 

 leaflets in a saturated chloral-hydrate solution; by about 100 times magnifying power 

 the cells will then be easily visible. In unprepared material, when magnified less, 

 they often resemble long and fine (pale *t shining) streaks at the margin or .on the 

 under surface of the leaflets. For the characters of these cells, see'Hieron. in 

 Engl. & Prantl, Nat. Pfl.Fam., I 4 , (549. 



(') I don't follow Hieronymus' natural arrangement given in Engl. & Prantl, 

 Nat. Pfl.Fam., I 4 , p. 569712, it beeing too intricate and too difficult for practical 

 use, but at any rate it may be decidedly advisable to consult it besides mine as 

 well as that given in Warb., Mons., I, p. 100112. 



It is to be observed that several species are difficult of determination because 

 cf incomplete description. Furthermore the sections and groups are passing more or 

 less gradually into each other so that it is impossible to draw the precise limits 

 between them, and the characters given in both sections and groups are. for the 

 greater part, those of the typical forms. 



