225 
Lithothamnion calcareum Ellis et Sol. var. norvegicum Areschoug, Observ. phycolog. III. 1875, p. 4. 
Lithothamnion coralloides Crouan f. norvegica (Aresch.) Foslie, Norw. Forms 1895, p. 62, tab. 16 fig. 1-11. 
According to FOSLIE, this species is almost always freely developed on the 
bottom (Remarks p. 66). The specimens found in the Danish waters were all loose. 
FosLıE has referred them all to f. pusilla which, in his opinion, is “perhaps the 
typical form of the species”. He observes however (l. c. p. 64 and 67) that they 
“partly approach stunted forms of L. nodulosum f. gracilescens”. They give off 
branches in all directions and become up to 3 cm (more rarely 3,5 cm) in diameter. 
The anatomical structure is not very different from that of L. glaciale. According 
to Mme LEMOINE, the cells are in the greater part of the frond rectangular, while 
Fig. 142. 
Fig. 141. Lithothamnion glaciale var. Granii. A, 
Lithothamnion glaciale var. Granii. Vertical section of sporangial sporangium; the process of division not 
conceptacle with ripe sporangium. 350:1. yet completed. B, ripe spore. 390:1. 
near the periphery they are ovoid. This may be so, but it frequently happens that 
rectangular cells in the inner parts of the frond alternate with ovoid ones (fig. 143 C). 
The change may take place at the distinctive lines between the zones or indepen- 
dently of them. The zones are limited by somewhat irregular lines staining deeply 
by hæmatoxyline, and the staining power of the single layers may sometimes be 
a little different, but the limit between such zones is not always marked as a blue 
line (fig. 143 C). The irregular course of the distinctive lines is probably in accordance 
with the irregularity of the increase. Transverse fusions between the cells frequently 
occur, though not so frequently as in L. Granü, and not uniting so many cells as 
in that species. The cells are 8—14y long, 6—9 4 broad; the rectangular ones are 
11—14y long, 6—7 4 broad. The central tissue shows a different aspect in trans- 
verse section, according to whether the section has fallen in a zone with rect- 
angular or with roundish cells. The appearance of the starch is variable. It may 
appear in great quantities in the more deeply stained and in the less stained 
zones as well, all the cells being filled with starch grains except the outermost ones. 
In other cases it is entirely or almost entirely wanting. 
Conceptacles were found in specimens from most of the localities named below; 
D. K. D. Vidensk. Selsk. Skr., 7. Række, naturvidensk, og mathem, Afd. VII. 2. 29 
