KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:0 5. 89 



rent forms of which are represented by fig. 6 — 10, are sometimes flattened, with the 

 branchlets arranged almost palmately, sometimes obpyramidal, in larger specimens about 

 2 — 3 cm. long. In typically developed specimens the branches are erect, fastigiate, 

 and straight, in others they are spreading and more or less curved, those of the last 

 order being 5 — 10 ram. long, terete, or somewhat compressed, either cylindrical, or 

 tapering, or slightly enlarged towards the tip, with the ends rounded, 1,5 — 2,5 mm. in 

 diameter. 



The structure of the frond. At the broken end of a branch there always appears 

 a more solid, central part of greater or lesser circumference. A pellucid, transverse 

 section, obtained by grinding, shows this central part to be composed of a very dense 

 tissue of angular, iso-diametric cells with very small cell-rooms and very thick walls 

 marked by double contours; fig. 12 and 15. This is surrounded with numerous, pretty 

 regularly concentric layers, distinctly marked against one another and resembling the 

 yearly rings of a dicotyledonic stem, every one of which is found on the transverse 

 section to be formed of comparatively large-roomed cells, which are arranged in pretty 

 regularly concentric and radiating rows. Of these cells the inner ones appear longer, 

 rectangular, the outer ones shorter, almost square. In the layer nearest the central 

 part the cells are less regular and in the outermost layers the difference in length is 

 rather imperceptible. A cut made thin by grinding, parallel to the longitudinal axis 

 of a branch, fig. 13 and 16, shows the branches to consist of superposed, generally 

 distinctly separate, very regular, cup-shaped layers of tissue, whose cells are arranged 

 in rows radiating in the shape of a fan. The lower, inner cells of each of these layers, 

 on an optical longitudinal section, are rectangular, 20 ju. long at the most; the upper 

 ones are square, with somewhat thicker walls than the others, and like these, 5 — 8 

 /n. thick. 



Organs of propagation. Sporocarpia unknown. The conceptacles of the sporangia 

 occupy a generally sharply defined zone below the tips of the branches, and commonly 

 occur in great numbers, forming what may be called a sorus; fig. 11. Hence the name 

 of the present species. They are always superficial, never growing down into the frond 

 nor becoming overgrown by it; so that traces of old organs of that kind are never to 

 be seen in the interior of the frond (cf. fig. 12 — 13). This fact, in this species as well 

 as in several others, together with which it appears to form a well marked group, depends 

 apparently on the thickening meristema of the frond lying below the basal surface of 

 the conceptacles. They are circular in circumference, very little prominent, small, 

 scarcely perceptible to the naked eye. The roof is slightly convex, traversed by nu- 

 merous canals, which are transversely 5 — 6-angular and filled with a gelatinous sub- 

 stance, and the orificial cells of which are somewhat different in shape from the other 

 cortical cells of the roof; fig. 18. The sporangia are tetrasporic, oblong or club-shaped, 

 somewhat variable in size, but generally, aft'er the formation of spores has begun, about 

 95 i«. long and 20 fA. thick; fig. 19. 



Remark on the relation of this species to other species described. L. soriferum descri- 

 bed as a new species, is more nearly related to L. fasciculatum Lam. than to any other 

 known species. However, it cannot in my opinion be identified with this species, which 



K. Vet. Akad. Handl. Bd 20. N:o 5. 1^ 



