66 Veit Brecuer Wirrrock. 
Among the specimens I have had occasion to examine, not one has had the 
lower part of the thallus left; thus the nature of the rhizoid is unknown to me. 
Sterile specimens. I have seen but one such specimen. The cauloid of 
the thallus had branches of three degrees. Those of the l:st and 2:d degree were 
mostly found in pairs, opposite to each other, more seldom they were single; those 
of the 3:rd, on the contrary, were single. The lower part of this specimen I have 
represented pl. 1, fig. 12. From the cauloid proceed obliquely downwards two 
rather long cells, of which I suppose the one, marked rh, to be the rhizoid, and 
the other, marked ac, to be an accessorial (rhizine) branch on the basal cell of the 
cauloid, analogous to the one represented pl. 4, fig. 7 ac after a sterile specimen 
of P. kewensis nob. 
Measurements. Fertile specimens. The principal filament of the cauloid 
is on an av. 120 w thick. The limits of variation are 90 and 150 uw. The branches 
of the 1:st degree are in general 90 w thick, varying between 70 and 115 uw. Those 
of the 2:d degree are also about 90 w thick, and those of the 3:rd degree about 
85 wu. The length of the vegetative cells varies between 6 and 20 times the 
thickness. The inclosed cask-shaped spores (i. e. the single ones in the principal 
filament, and the upper one in the pairs of twin spores) are on an ay. 144 w thick 
and 232 w long. The limits of variation are indicated by ji? 1% 33° uw. The lower 
ones in the pairs of twin spores are on an ay. 113 w thick and 179 w long. They 
vary between ‘-@ and 5° w. The single cylindrical spores are on an ay. 85 mw thick 
and 135 w long. They vary between 4) 473 72 U- 
The measures of the sterile specimen are as follows: the principal fila- 
ment 115--130 w, the. branches of the 1l:st degree 100—125 w,.the branches of the 
2:d degree 90—100 w, the branches of the 3:rd degree 75—80 «w, the rhizoid (?) 
95 w. - 
Affinities and Differences. ‘This species shows a near relationship to P. poly- 
> morpha nob. and P. Roettleri (Roth) nob. Its most remarkable character is, that 
the spores in the principal filament occur, as a rule, two and two end to end. 
(If an exception from this rule takes place now and then, a subsporal branch has 
been developed, as has been indicated above, instead of the lower one of the 
spores.) The ramification is feebler in this species than in P. Roctileri (Roth) 
nob., but somewhat stronger than in P. polymorpha nob. 
8. Pithophora Roettleri (Roth) nob. 
Synon. Ceramium Rocttleri Roth Catal. Bot. ILI, p. 123. 
Cladophora acrosperma Kiitz. Phye. gener. p. 265. 
A Roettleri’ Kiitz. Spee. Alg. p. 409; Tab. Phyc. Band. IV, 
pag. 10, tab. 46. 
Diagnosis: Principal filament of the cauloid part of the thallus 
in fertile specimens on an average 165 y thick, with branches of three 
degrees; branches of*the first degree three in a whorl, branches of the 
second and third solitary or opposite in pairs; spores solitary (rarely in 
