361 
filaments had usually free ends; they penetrated a layer of detritus bound to- 
gether by animal secretion, in which the plants grew without fixing themselves on 
the algæ covered by the layer of detritus (fig. 295 A, comp. 
Kuckuck 1894 fig. 22). The outer cells in these filaments 
lengthen, become gradually poor in contents and are finally 
thrown off, but the innermost cell often remains for a long 
time and every trace of the decaying of the outermost cells 
is then effaced, the wall of the upper end of the cell being 
rounded (fig. 295 B). In Fig. 296 the scar is still visible (x). 
In other cases, the rhizoids fix themselves on the substratum 
forming an adhesion disc composed of a number of radiating 
cell-filaments. According to BERTHOLD (1882, p. 607) the cells 
of the rhizoids afterwards shorten, the cells becoming barrel- 
shaped and the cell-wall incrassated. Such rhizoids sometimes 
arise at a certain distance from the substratum, as shown in 
fig. 296, where the rhizoid has fixed itself to the mother axis 
of the pinna and formed an adhesion disc embracing it. 
The tetrasporangia are placed laterally on the pinne, 
borne on a one- or two-celled stalk. They are larger than 
those of A. Plumula, 
a J 
A | algen, p. 71). On the other hand, the cysto- 
Antithamnion Petes as is produced from CARPE mentioned fand fisuned Dy J. 
the basal joint of a pinna. B, tetrasporangium. 200:1. ÅGARDH (1879) as consisting of several 
lobes. 
The species has been found only in a few places in the Limfjord and in Katte- 
gat. It has been gathered in June to November, growing on stones and wood (piers) 
and on other Algæ. In the harbour of Frederikshavn it usually occurs in the 
creeping form radicans which may probably under favourable conditions grow out 
as the typical erect form. 
Fig. 296. 
Antithamnion cruciatum. 
73—102 uw long, 51 Lower part of plant; a rhi- 
==68 u broad. They zoid has fixed itself to the 
stem. 110: 1. 
were met with in 
July. Sexual organs were not observed. 
They generally seem to be rather rare; Har- 
vey (Phyc. Brit.) did not know them and 
Hauck too did not mention them (Meeres- 
Localities. Ns: 13'/: miles N.E.'/2 E. of Hanstholm light-house, 23m, C. A. J., very small 
specimen Oct. 1922. — Lf: Off Hanklit, Thisted Bredning, on Fucus; MK, Holmtunge Hage, c. 2 meters’ 
depth. — Kn: Harbour of Skagen (November 1911, Kramp); harbour of Frederikshavn, berths on the 
end of the moles and in other places on piers. — Ks: aU off Lumbsaas, 13 met. 
