On the Pithophorace^e. 



57 



cask-shaped with the upper end conical and the top somewhat rounded. Twin 

 spores occur not seldom, and are formed by terminal cells as well as by inclosed 

 (pi. 6, figs. 4, 5 ,', O- 



The rhizo'fd part. Only two of the examined specimens have been so 

 perfect as to have the rhizoid part of the thallus remaining-. In the one, repre- 

 sented pi. <), fig. 2, the rhizoid consists of four vegetative cells forming a single 

 series. In the other, represented pi. (3, fig. 3, the rhizoid has an uncommonly pow- 

 erful development. It is richly ramified, with branches even of two degrees, and 

 is also sporiferous, having both terminal and inclosed spores. In neither specimen 

 the limit between the cauloi'd and the rhizoid is so strongly marked as is usually 

 the case in Pithoplwracece. 



Sterile specimens resemble the fertile essentially as to their ramification. 

 The branches of the l:st degree are, however, still more frequently placed opposite 

 in pairs to each other (pi. (3, fig. 1). Only in one specimen I have seen the 

 rhizoid part of the thallus, and in this it consisted of only one cell (pi. (3, fig. 1). 



Measurements. Fertile specimens. The cauloi'd. The vegetative cells 

 of the principal filament are on an average 70 fi thick. The smallest thickness 

 observed is 55 and the greatest 90 /(. The vegetative cells in the branches of 

 the l:st degree are on an av. 58 thick. They vary between 50 fi and 70 fi. 

 The thickness of the branches of the 2:d degree is on an av. 55 and of those 

 of the 3:rd degree 53 fx. The length of the vegetative cells varies between 5 and 45 

 times the thickness. The top cells are the longest, as usual. — The inclosed spores are on 

 an av. 114 /t thick and 230 fx long. The limits of variation are indicated by ^ 7 ° 

 iilo 320 P" ^ ne terminal spores are on an av. 95 fi thick and 214 fi long. They 

 vary between jo, m /( . 



The rhizoid. The thickness of the principal filament is on an av. GO /i, 

 that of the branches of the l:st and 2:d degree 50 ft. The length of the rhizoid 

 cells exceeds the thickness 6 to 40 times. The spores which I have found in the rhizoid 

 of the specimen represented pi. (3, fig. 3 are, the inclosed one 100 fi thick and 

 255 [i long, and the terminal one 85 (i thick and 240 /i long. 



Sterile specimens. The cauloi'd. The thickness of the principal filament 

 is on an av. 86 it. It varies between 85 f.i and 90 /t. The branches of the l:st 

 degree are on an av. 72 ,u thick, those of the 2:d 65 /u, and those of the 3:rd 60 /<. 

 The length of the cells varies between 6 and 50 times the thickness.. The rhi- 

 zoid of the single specimen in which I have had occasion to observe this part 

 of the thallus, was 55 fi thick. 



Affinities and Differences. P. oeclogonia (Mont.) nob. is most nearly related 

 to P. Jcewmsis nob. It differs from this species, as well as from the other species 

 belonging to this section (P. isosporece) by a considerably stronger development of 

 the system of ramification in the sterile specimens as well as especially in the fer- 

 tile ones. But one of the other species possesses branches of the 3:rd degree, and 

 in no one of the others opposite branches occur so often in the fertile specimens. 

 Characteristic in this species are also the frequent occurrence of subsporal branches 

 and of twin spores. 



Nova Acta Reg. Soc. So. Ups. Ser. III. 8 



