256 



7. Melobesia niicrospora sp. n. 



Frondes suborbiculares, ssepe confluentes, 1 — 2 mm diametro, excepta parte 

 marginali polystromaticse, e filis verticalibus usque ad 7-cellularibus compositse; 

 cellulis filorum 6 — 8 n latis, diametro vulgo 1 — 2-plo longioribus, cellulis strati 

 basalis plerumque brevioribus. Cellulse corticales desunt. — Conceptacula nume- 

 rosa contigua vel subcontigua. — Conceptacula sporangifera depresso-hemisphserica 

 vel conica, diametro 120 — 140/^, ostiolo vix papilioso, medio nonnunquam columella 

 munita. Sporangia parva, 17 — 24/Honga, (9 — )11 — 12(— 16) « lata, semper 4-partita. 

 Sub conceptaculis 1—4 strata cellularum vegetativarum. — Conceptacula mascula 

 parva, paulo prominula vel omnino immersa. Spermatangia elongata vel clavata, 

 fundum planum conceptaculi investientia. Spermatia lineari-clavata, nonnunquam 

 leniter curvata, c. 6 a longa, 2 // lata. — Conceptacula feminea ut videtur forma 

 structuraque cone, sporangiferis similia. — Hab. in fronde Furcellarice fastigiatce. 



The species here described has only been met with once, viz. on a specimen 

 dredged in the bay of Aarhus. The specimens were determined by Foslie as Melo- 

 besia Lejolisii Rosan. forma, but as will be seen from the description given here, 

 it is very different from that species, particularly in the structure of the frond and 

 the small dimensions of the sporangia. 



The greater part of the frond is polystromatic ; only the marginal part is 

 monostromatic, but it is early divided by horizontal walls, and the frond is then 

 composed of vertical filaments composed of from two to seven or eight cells. These 

 filaments are usually 6—8 // broad and consist of cells of varying length, usually 

 1 to 2 times as long as broad. The cells of the basal layer are rather varying in 

 height, but they are usually lower than broad. There is thus no contrast between 

 the basal layer and the perithallium. Seen from above, the cells of the basal layer 

 show a breadth of 5 — 8//, about the same length or a little more, and appear to be 

 frequently connected by lateral fusions (fig. 176 C). Such fusions may also occur 

 between cells above the basal layer, but transversal pores (secondary) nowhere 

 occur. It is remarkable that cortical cells as those characteristic of the other Melobesia 

 species do not occur. When seen from above, the superficial cells present them- 

 selves as nearly quadratic cells arranged in rows, but no small cells cut off from 

 them appear, not even after staining with h?ematoxyline, by which treatment the 

 walls of all the outer cells and the cuticle are very intensely stained. Hair-cells 

 were not observed. 



The coi\ceptacles are numerous, occupying most part of the crust, frequently 

 contiguous, giving the frond a verrucose aspect. The sporangial conceptacles are 

 depressed hemispherical or more rarely low conical. A more or less developed 

 central narrow columella is not infrequently present. The sporangia which do not 

 occupy the centre of the conceptacle are remarkably small; [they are always four- 

 parted, the three septa approaching each other in the middle of the sporangium 

 (fig. 177 A). When seen from above, the small ostiole is seen to be surrounded by 



