KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 20. N:0 5. 97 
Lithothamnion intermedium nob. 
L. fronde subglobosa, dilute rosea, scabriuscula, diametro circa 7 cm., parte centrali solida, plus minus 
distincte lobata, ramos vel breves, verrucweformes vel longiores usque 4—5 mm. altos, basi 2 mm. crassos vel 
simplices, conico-cylindricos, apicibus obtusis, vel infra apicem uno alterove ramulo brevissimo, verruczeformi 
preeditos undique emittente; conceptaculis sporangiferis demum innatis, minutis, convexiusculis at parum promi- 
nentibus, creberrimis, nullo ordine in tota fronde sparsis; sporangiis quaternas sporas foventibus, 130—150 «. 
longis, cirea 40 w. crassis; Tab. 4. 
Description of the species. External shape. he plant forms spherical or spheroi- 
dical balls, which, when older, are about 7 cm. in diameter (fig. 1). In several of the 
specimens examined by mesthere was nothing included in the interior of these globular 
masses; others encompassed small stones. The frond is constituted of a thick central con- 
tained portion intersected with cavities and canals, and projecting in more or less distinct, 
simple or divided, clumsy, thick lobes. These carry partly simple, short, and wart- 
like, partly longer and branch-like processes. The latter reach a length of 4-—5 imm., 
with a diameter of about 2 mm. at the base. They are sometimes simple, conically 
cylindrical, obtuse, sometimes furnished with one or two, generally short, wartlike side- 
branches below the tip. The plant is more or less deeply rose-coloured. Its surface 
is uneven, on account of local, scaly thickenings of the surface. As in the preceding 
species, the central mass is rich in holes after boring-muscles, and in passages produced 
by worms. 
Structure of the frond. The fracture is white or faintly rose-coloured with rare, 
small, yellowish-brown dots — the grown-in conceptacles of sporangia. In longitudinal 
section the processes show distinct cup-shaped layers, although these are not so re- 
gular as for inst. in L. soriferum. ‘The inner cells of these layers, in longitudinal section, 
are rectangular with rather thin walls, the outer ones have more rounded cell-rooms 
and somewhat thicker walls. The diameter of the former amounts to 7 w., their 
greatest length to about 15 uw. fig. 8. A cross cut of a process shows essentially the 
same structure as in the preceding species, differing only by the cells of the outer 
concentric layers having thinner walls and a greater length in the direction of the 
radius (fig. 4, 6, 7). The surface cells of the frond are isodiametrical in a tangential 
section, 4—6-angular, about 10 uw. in diameter, with walls 2,5; «. thick (fig. 9). 
Organs of propagation. The conceptacles of sporangia are spread over the whole 
frond and become’ grown over in the present species as in the preceding. Although 
there are certainly found older grown-in organs of this kind nearer the centre of the 
processes, most of them are peripherical. The superficial ones are but little prominent 
above the surface of the frond, small, with slightly convex roof (fig. 3). This is tra- 
versed with numerous gelatiniferous canals. In none of the specimens examined | have 
seen these reach to the surface of the roof, and from that cause do not know how 
their orificial cells may be constructed. The sporangia are tetrasporic, spindleshaped- 
cylindrical or claviform, 130—150 wu. long, about 40 «. thick (fig. 10). 
Relation of the present species to others. The present species is probably most 
closely related to L. glaciale. By its general habit and its grown-in sporangia, it re- 
minds one most of this. In other respects, however, its structure approaches more 
» 
K. Vet. Akad. Handl. Bd 20. N:o 5. LS 
