JoHnson—Pogotrichum hibernicum. 9) 
Laminarie, already noted by Reinke, are similar to those of P. 
hibernicum. Thus I am led to believe that the two genera Lilosiphon 
and Pogotrichum are one and the same, and ought to be united, 
and that LZ. Laminarie and P. hibernicum, if not one species, are 
very closely allied. I prefer to go no further than this until I 
have had an opportunity of examining living material. 
As regards the other affinities of Pogotrichwm, it is a member 
. of Kjellman’s group Enceliacee, containing amongst other genera, 
Asperococcus, Scytosiphon, Punctaria, Desmotrichum, and Litosiphon. 
Pogotrichum, like Litosiphon, is radially constructed, and thus 
differs from Punctaria, Grev., and Desmotrichum, Kitz. Itshould 
be remembered that ZL. pusil/us may appear sub-bilateral in cross- 
section. The genus Desmotrichum, founded by Kitzing,” 
suppressed by Thuret and Bornet,? and restored by J. Reinke,* 
is said to differ from Punctaria in having its pheosporean hairs 
solitary, and its sporangia projecting. Plate 1., fig. 7, of 
Punctaria shows the plurilocular sporangia projecting very con- 
siderably. As the hairs, especially in young plants of Punctaria, 
may be solitary, and as Reinke’ himself figures a section of 
Desmotrichum undulatum, J. Ag., showing three hairs side by 
side, it is probable that Desmotrichum, Kiutz., ought not to be 
regarded as more than a sub-genus of Punctaria, Grev., a view in 
which I have, I am permitted to state, the support of Dr. Bornet. 
The affinity of Pogotrichum to Stictyosiphon is by no means remote. 
Pogotrichum might, with some reason, be described as an 
unbranched Stictyosiphon. A magnified figure of a Pogotrichum 
filament is not unlike a figure (natural size) of a Stictyosiphon, the 
hairs of Pogotrichum with their basal growth being regarded as 
potential branches,® it is not difficult to see how a plant of 
Stictyosiphon could be derived from a Pogotrichum filament. 
1G. B. de Toni, ‘‘Systematische Uebersicht d. bisher bekannten Gattungen d. 
echten Fucoideen’’ (Flora, 11. of Jahrg. 49, s. 171-182). 
2 Kutzing, Tab. Phyc. vr., t. 4. 
3Thuret et Bornet, “ Ktudes Phycologiques,”’ p. 15. 
4J. Reinke, ‘‘ Atlas deut. Meeresalgen,’’ r. 
5 J. Reinke, ‘‘Atlas deutscher Meeresalgen ’”’ (Taf. 11., fig. 11), op. ibid. 
6 In one tuft of Pogotrichwm hibernicum the apical hair of a filament from which 
the zoospores had escaped had grown in such a way as to form a new filament at the 
apex of the first. 
