JoHnson—Pogotrichum hibernicum. 7 
as pointed out by Reinke,’ endophytic also. A more noteworthy 
example of an apparently important difference of habit in closely 
allied forms is described* by Sauvageau in Ectocarpus fasciculatus, 
variety abbreviatus. Two forms of this variety, growing on 
Laminaria flexicaulis, were examined; one is entirely epiphytic with 
abundant sporangiferous rhizoids, the other is endophytic also. 
Affinities of Pogotrichum, Rke.—The affinity of Pogotrichum to 
Litosiphon, Harv., is so close, that Reinke in writing to me states 
that had he known of the Kilkee plant he would have hesitated 
before founding the genus Pogotrichum. In the last number of 
his ‘‘ Atlas deutscher Meeresalgen,” Reinke compares the four 
plants Pogotrichum filiforme, P. hibernicum [“the Johnsonian 
plant” |, Litosiphon pusillus, L. Laminarie. It is stated that— 
1. The individuals with plurilocular sporangia, of P. hibernicum, 
agree with the filamentous specimens of P. filiforme. 
2. The individuals with unilocular porate of P. hibernicum, 
are like those of Z. Laminariae. 
3. Before, however, uniting the two genera it will be necessary 
to find plants of true Zitosiphon species with plurilocular sporangia, 
like Pogotrichum individuals with plurilocular sporangia. (P. 
Jiliforme, with its plurilocular sporangia, is not, as one might 
suppose at first thought, the missing state of Z. pusillus which is 
known up to the present with unilocular sporangia only). 
4. Though the individuals of Poyotrichum consist of uni- 
seriate as well as multiseriate filaments, those of Lrtosiphon are 
always multiseriate. 
I have been enabled to examine dry, authentic material of 
Litosiphon Laminarie, Harv., from the following sources :— 
1. Through the kindness of Dr. E. P. Wright, Dublin, material 
of the type specimens, preserved in the Trinity College Herbarium, 
was at my disposal. One specimen was labelled “ Bangia laminarie, 
Lyngb. [and was collected by] Mr. Moore [the late Dr. D. Moore 
of Glasnevin] in Co. Antrim”; another “Ball and Thompson, 
1834, Arran”; another “ W. Andrews, Inch, Dingle Bay.” 
2. A specimen in the late Dr. D. Moore’s own collection of 
1J. Reinke, ‘‘ Atlas deutscher Meeresalgen,”’ J. c. 
*C. Sauvageau, ‘‘Sur quelques algues phéosporées parasites,”’ p. ‘38 (Jovrn. de 
Bot. v1., 1892). 
