111 
walled, 3 to 4 times as long as broad, the sporangia 17,5 -19 » long, 14—15 (16) a 
broad. As a contrast to these some specimens may be mentioned which were 
found growing on Porphyra umbilicalis in Thyborøn Channel (Lf); they agreed on 
the whole fairly well with this form, but the filaments were only 7—8 y thick. 
Such a small thickness I have otherwise never observed in the specimens referred 
to this form, though certainly in f. secundata which occurs along the west coast of 
Jutland; I imagine that these specimens 
may have originated from f. secundala 
but have developed ina more sheltered 
locality. It deserves notice that groin 
no. 63 is more sheltered than no. 62 
where f. secundata was found growing, 
and that the species has otherwise not 
been found in the Limfjord with the 
exception of at Hals at the eastern en- 
trance of the fjord where f. secundata 
has been met with. — For the rest the 
specimens referred to this form are on 
the whole homogenous. 
This form has been found in all 
the Danish waters within Skagen, from 
low-water mark to 11,5 meters depth. 
The specimens found at Bornholm are 
typical but not very vigorous and with 
little branched filaments. It was mostly 
met with in the summer months and is 
undoubtedly mainly a summer Alga; for 
the rest it has been met with in the B 
months April to November, in all cases AD 
with sporangia. It was most frequently 
found growing on Polysiphonia violacea Fig. 38. 
and nigrescens , further on Ceramium Chantransia virgatula ß, tetrica. A, B and C, young plants 
5 5 seen from above and from the side. D, branched filament 
rubrum a. 0. species, Cystoclonium, Zo- with tetrasporangia mostly on opposite branchlets. E, fila- 
stera-leaves, Porphyra umbilicalis and ment with sessile tetrasporangia. F, two cells showing the 
Aa i chromatophore. 265: 1. 
Sertularia pumila. 
Localities. Lf: Thyborøn Channel, groin no. 63, otherwise not found in the Limfjord. — Kn: 
Harbour of Skagen; Hirsholm; Frederikshayn (Th. Mortensen, !); Nordre Ronner; stony reef by Jegens 
Odde (GM). — Ks; Lysegrund; D, 11,5 meters. — Sa: Ronnen in Begtrup Vig; Kalo Rev; AS, Mejlgrund. — 
Lb: Fæno. — Sh: Kertinge Vig. —- Sm: Petersværft; Guldborgsund. — Su: BQ, off Ellekilde; Helsingør; 
Copenhagen. — Bm: QP, Kalkgrund; QR, Gyldenløves Flak. — Bb: Rønne; off Allinge. 
B, tetrica nob. 
Filaments (8—) 9—12 thick, cells 2—4 diameters long, sporangia on opposite 
branchlets or sessile on the jong filaments, all or partly tetrasporous and then 19— 
22 long, 13—17 broad. 
