122 M. FOSLIE. [1905 



a denominated form, referring it to each of the three forms last 

 mentioned. Having, however, a comparatively small material of 

 this form, peculiarly from the Mediterranean, I think I ought to 

 admit it for the present as an independent one. It was first de- 

 scribed by Crouan and stated by him as carrying bisporic spor- 

 angia, and this seems to be the case everywhere in the northern 

 areas. The conceptacles of northern specimens partly approach 

 or agree with those of f. intermedia, but are often less prominent 

 and not so well defined as generally is the case with this form, 

 partly correspond with those of f. macrocarpa. Thus on the west 

 coast of Ireland I fell in with a form, growing on a coarse Coral- 

 Una officinalis, whose conceptacles completely resembled those of 

 f. macrocarpa, up to about 600 fi in diameter. On the other hand, 

 it is rather probable that the form from the Mediterranean with 

 tetrasporic sporangia, mentioned by Solms Laubach 1. c. should 

 be identical with f. australis. I have not yet fallen in with spe- 

 cimens with such sporangia. In the Adriatic Hauck mentions 

 1. c. p. 266 and 575 that the alga appears now with tetrasporic 

 sporangia, now with bisporic ones. Perhaps it is here identical with 

 faintly developed specimens of f. australis and of f. intermedia, 

 both of which occur in the same area. As far as I have seen, 

 the form is alwa3 7 s most vigorously developed, and the concep- 

 tacles grow largest on coarse specimens of the host plant, corre- 

 sponding to the development of the forms australis and intermedia 

 on different substrata. The bisporic sporangia are 60 — 110/-'- long 

 and 30—60 p. broad. 



The form Laminarios is the least varying form of this species. 

 It very nearly approaches f. macrocarpa and is in the main distin- 

 guishable from this form only b}^ the fact that the conceptacles 

 are mostly somewhat lower, partly not well defined either. It 

 occurs both on the stem and sometimes also on the hapters of 

 Laminaria hyperoorea and L. digitata. The sporangia are 60 — 

 100 /j. long and 30— 60 /* broad. They are recorded by Crouan 

 1. c. to be tetrasporic, but I have till now only seen bisporic ones. 



As to structure the species is also rather varying. The length 

 of the cells of the basal layer is three to eight times, sometimes 



