108 Rhodora [June 



is smaller in all' its dimensions, both of filaments and sporangia, with 

 fewer hairs, little investing gelatine, less regular erect filaments, and 

 with ])luriloeular sporangia persistent for some time after emptying. 

 Moreover it shows as a uniform coating on the host plant, rather than 

 as Elachista-like tufts. In fronds of Ilelmirifliocladia purpurea 

 (Harv.) J. Ag., San Pedro, California, July, 1S99. Mr/i. H. D. 

 John Man. 



103S. Hecatonema maculans (ColUns) Sauv. forma solutum, n. f. 

 Basal layer an open network, otherwise like the type, which grows in 

 the same locality on Rliodi/mruia pobnata (L.) Grev. On Castagnra 

 virrscpuft (Carm.) Thuret and A.sprrococcits cchinatus (Mert.) Grev., 

 Spectacle Island, Penobscot Bay, Maine, July, 1898. F. S. Collins. 



1084. Lamin'aria Agardhii Kjellm. forma zostericola, n. f. Very 

 delicate form, growing on floating Zostera marina L., Newport Harbor, 

 Rhode Island, A])ril. 1899. 3/r.s-. ]V. C. Simmons. 



LXXXIII. La.mixaria Agardhii Kjellm. forma angustissima, 

 n. f. Fronds extremely narrow in proportion to the length; stij)e 

 5 to 25 cm. long; lamina up to 8 meters long, 6 to 25 mm. wide. 

 The substance is firmer than in other forms of the species, and there 

 are no lines of bullae. The margin is even, not at all undulate, and 

 the width is nearly the same in all but the base, and in young plants 

 the tip. The dimensions given include the largest fruiting fronds 

 observed; a width of more than 15 mm. is unusual; and fronds 12 

 mm. wide and 250 cm. long are common. Forming a very dense 

 fringe just above and below low water mark, on rocks exposed to the 

 full force of the waves, Bailev's Island, Casco Bay, Maine, July 18, 

 1903. F. S. Collins.' 



834. Dilophus flabellatus n. sp. Frond reaching a length of 3 

 dm., dichotomous, in older plants sometimes with an apparent flexu- 

 ous rachis and alternate branches, 3-5 mm. wide at base, broadening 

 above to a width of 1-2 cm., all the divisions broadening upwards, 

 terminal segments rounded; base stupose for a short distance. Young 

 frond consisting of a single layer of large scpmrish cells, with a single 

 layer of small cortical cells, the latter arranged in longitudinal series, 

 and once to twice as long as broad; in older plants the margin is 

 thickened and has two layers of internal cells, often with two layers 

 of cortical cells ; walls of internal cells punctate. Oogonia, antheridia 

 and tetraspores on separate individuals, at first occupying the middle 

 part of the segments, leaving the margin free; ultimately often cover- 

 ing the whole width; oogonia scattered more or less densely, but not 

 usually in contact; antheridia in oval or oblong patches; tetraspores 

 in similar patches, sometimes becoming confluent. 



In young plants the branching is densely dichotomous with a 

 rounded outline to the frond, but some of the segments develop more 



1 This is the Laminnria mentioned by the writer in Bull. Torrey Bot. Club, Vol. VII, 

 p. 118, with the suggestion that it might be L. longipes Bory. , 



