I9i-j] Skottsherg: Pylaiella Posfehiae 157 



I regard this genus as distinct from Ectocarpus. I was inclined to 

 give it a more independent position, as the type of a new genus ; but 

 after having discussed the matter with Professor P. Kuckuck I have 

 abandoned this first idea. 



Bornet divided the genas Pylaiella in two subgenera, Eupylaiella 

 Born.- and Bachelotia Born. ("Note sur 1' Ectocarpus fulvescens 

 Thuret," liev. gener. cle hot., 1889), the first having numeroas, richly 

 branched, erect filaments, the latter scarce, with very few branches, 

 and including three species — P. fulvescens (Thur.) Born., P. Hooperi 

 (Crouan) De Toni, and P. nana Kjellm. Intercalary chains of uni- 

 locular sporangia have been found in them all. plurilocular only in 

 P. na)ia, where they have a peculiar shape, being branched as in 

 Streblonema fasciculatum Thur. Unilocular sporangia are unknown 

 in our new species, and there seems to be little hope of finding them. 

 Saunders collected sterile material in the spring, and late in August 

 he found plurilocular sporangia He suggests that the other kind may 

 occur later in the season. On my material, collected on September 27, 

 there is no trace of them, nor is anything of the kind to be seen on 

 material collected by Professor Setchell on November 4. Just as its 

 host, the epiphyte is probably an annual species, disappearing wdth 

 Postelsia during the winter. But even if unilocular sporangia were 

 to be discovered, arranged like the other kind, I can not find a suit- 

 able position for the new species in either of the two subgenera, for 

 it differs from both in the position of the sporangia and in the rami- 

 fication. The plurilocular sporangia are not intercalary, but terminal, 

 developed in a basipetal order. In some plants I have seen one or 

 two sterile cells breaking the otherwise continuous chain, not counting 

 the mother-cells of the branchlets. It is only the character of these 

 latter cells that would justify the use of the term "intercalary" in 

 this case, and, further, the fact that the different "internodes" are, 

 to a certain extent, independent of one another, .so that cell divisions 

 may have gone very far in a lower internode before all the sporangia 

 in the one above it are mature (pi. 19, fig. 4). In conformity with 

 this state of things, the divisions in a pair of branches may have almost 

 come to an end, and the upper sporangia already be emptied, before 

 the fertilization has advanced to the base of the internode just above 

 (pi. 19, figs. 4, 5). 



There is no Pylaiella in which we have a distinction between long 

 and short branches sucli as in our new species. In P. varia Kjellm. 



2 The name giveu ])y De Toni in Syll. Alg. 3, p. 351. 



