On the Pithophokace^. 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 ,; ./)• 



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

 perfect as to have the rhizo'id jiart of the thallus remaining. In the one, repre- 

 sented pi. 6, fig. 2, the rhizo'id consists of four vegetative cells forming a single 

 series. In the- other, represented pi. 6, fig. 3, the rhizo'id 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 'caulo'i'd and the rhizo'id is so strongly marked as is usually 

 the case in Fithophoraccce. 



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. 6, fig. 1). Only in one specimen I have seen the 

 rhizo'id part of the thallus, and in this it consisted of only one cell (pi. 6, fig. 1). 



Measurements. Fertile specimens. The cauloïd. The vegetative cells 

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

 observed is 55 ^t and the greatest 90 i.i. The vegetative cells in the branches of 

 the l:st degree are on an av. 58 /i thick. They vary between 50 ii and .70 /t. 

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

 of the ?r.xà. degree 53 ,<(. 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 ix thick and 230 i-i long. The limits of variation are indicated by ",'• ™ 

 I't'o 320 '*• "^^^ terminal spores are on an av. 95 ,u thick and 214 (.i long. They 

 vary between \';- j™; )^ n. 



The rhizo'id. The thickness of the principal filament is on an av. 60 ,« 

 that of the branches of the l:st and 2:d degree 50 i^i. The Icngtii of the rhizo'id 

 cells exceeds the tliickness 6 to 40 times. The spores Avhich I have found in the rhizo'id 

 of the specimen represented pi. 6, fig. 3 are, the inclosed one 100 i.i thick and 

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



Sterile specimens. The caulo'i'd. The thickness of the principal filament 

 is on an av. 86 ji. It varies between 85 ft and 90 /(. The branches of the l:st 

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

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

 zo'id of the single specimen in which I have had occasion to observe this part 

 of the thallus, was 55 ft thick. 



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

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

 belonging to this section (P. isosporcœ) 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 snbsporal branches 

 and of twin spores. 



Nova Acta Reg. Soc. Sc. Ups. Scv. III. ' 8 



