In the Arctic Sea Ceratocolax Hartzii has been found with ripe tetrasporangia 
in spring (March, May), just as in the Danish waters. But it is remarkable that 
unripe nemathecia have been met with repeatedly in summer, June (West Green- 
land), August (East Greenland), July and September (Arctic America, K. ROSENVINGE, 
1926). It seems probable that nemathecia occur all the year round in the Arctic Sea. 
The systematic position of the genus Ceratocolax remains uncertain so long as 
cystocarps are unknown, and the sex organs are only known as imperfectly devel- 
oped and abortive. An affinity to the genus Phyllophora on which it is parasitic is 
highly probable. 
The species is spread in nearly all the Danish waters, in particular the inner, 
more protected waters where it occurs at depths from 2 to 18 metres, perhaps most 
frequently on Ph. Brodiei f. concatenala. It is met with in all seasons and reaches 
a diameter of from 2.5 to 5 mm. The greatest diameter, 5 mm, was met with in 
specimens gathered in May and September. 
Localities. Ns: On Ph. Brod. f. concatenata at Blaavandshuk (C. M. Poulsen). — Lf: LY, on Ph. 
Br. concat., between Gellerodde and Inderrön at Lemvig. — Kn: At Friis’ Sten between Vesterø and 
N. Renner, on Ph. Br. typ. 3m. — Ke: HY, Store Middelgrund, 15 m, on Ph. Br. typ.; ad Nakkehoved 
(Lyngbye), on Ph. Br. typ., washed ashore. — Sa: fN*, off Ballen, Samsø, 11.3 m, on Ph. Br. typ.; Hof- 
mansgave, on Ph. Br. concat., numerous specimens gathered by Hofman Bang, Lyngbye, Car. Rosen- 
berg. — Lb: Off Snoghøj; Fænø Sund; dE, Holst’s Banke 8—13 m, on Ph. Br. typ.; dH and dH’, east 
of Hesteskoen, 15—19 m, on Ph. Br. typ. — Sf: CA, Højen near Faaborg, on Ph. Br. concat. and filiformis 
(fig.517 C).— Sb: Off Stavreshoved at Kerteminde; Bay of Kerteminde, on Ph. Br. concat.; NS, between Knuds- 
hoved and Slipshavn, on Ph. Br. concat.; XS, Kloverhage south of Nyborg, 5—6 m, on Ph. Br. concat.; 
fP, ‘/2 mile east of Hov lighthouse, 10 m, on the same; UJ, near the broom at Onsevig, 7.5 m, on the same. — 
Su: OH, north of Lous’ Flak, 10 m; at Dragør, on Ph. Br. concat. — Bw: bV, N.E. of Kobbel Skov, 
7—13 m, on Ph. Br. conc.; bY, off Sønderskov, Sønderborg 11 m, on the same; cD, Middelgrund south 
of Als., 8—12 m, on Ph. Br. typ. 
Ahnfeltia E. Fries. 
1. Ahnfeltia plicata (Huds.) Fries. 
El. Fries, Corpus florar. provincial. Sueciæ. I. Flora Scanica 1835, p. 310; J. Agardh, Sp. g. o. Alg. II 
pars I, 1851, p. 311; N. Wille, Bidr. (1885) pp. 13, 15, 50, plate II, figs. 11—12, plate V, fig. 52; 
B. Jönsson, Dickenwachst. 1891; Buffham, Anther. (1893), p. 302, fig. 43, 44; Schmitz, Actinoc. 
1893, p. 397; Printz, Trondhjemsfj., (1926), p. 63; Gregory, New light on the so-called parasitism 
of Actinococcus aggregatus K. and Sterrocolax decipiens Schm., Annals of Bot. Vol. 44, 1930; 
Chemin, Ahnfeltia plicata Fries et son mode de reproduction. Bull. soc. bot. de France, t. 77, 1930, 
p. 342; Kolderup Rosenvinge, The reproduction of Ahnfeltia plicata. K. D. Vid. Selsk. Biol. Med- 
delelser, X, 2, 1930. 
Fucus plicatus Hudson Fl. anglica, ed. alt. 1778, p. 589. English Botany, Vol. 16, 1803, plate 1089. 
Fucus albus ? Oeder, Flora Danica, tab. 408, 1768. 
Gigartina plicata Lamouroux, Thalass. 1813, p. 48; Lyngbye, Hydr. 1819, p. 42. 
Gigartina Griffithsie Lyngbye Hydr. 1819, p. 43, tab. 11 C, (non Turner)’. 
* An examination of the specimens from Funen referred by LyxsByE to Gigartina Griffithsiæ 
has shown me that the “tubercula” interpreted by LyneByE as “fructus” are not nemathecia but 
attachment discs of Cystoclonium purpurascens growing on Ahnfeltia plicata. 
