1900] Setchell, — The New England species of Laminaria 143 
DicrrAT;E. Blade split longitudinally into several or many segments. 
Mucilage ducts present in both stipe and blade. 
1. L. platymeris De la Pylaie. 
Mucilage ducts absent in the stipe, present in the blade. 
Stipe stout and decidedly compressed above. 
2. L. digitata (L.) Edm. 
* TL ensifolia Le Jolis. 
" — f. typica Foslie. 
v * — f. complanata Kjellman. 
Stipe slender and flexible, slightly if at all compressed. 
Blade undivided or split into few and comparatively broad segments. 
3 L. intermedia Foslie. 
A f. Jongipes Foslie. 
b b f. cucullata Foslie. 
d “ f. ovata Foslie. 
Blade split into many and narrow segments. 
4. L. stenophylla Harvey. 
SrMPLICES. Blade undivided, elongated. 
Stipe solid to the very apex, without mucilage ducts. 
Mucilage ducts present in the blade. 
Ip. L. saccharina (L.) Lam’x. 
f. normalis Setchell. 
» x f. caperata Farlow. 
d iz f. Phyllitis Le Jolis. 
Mucilage ducts absent in the blade. 
6. A Agardhii Kjellman. 
eg f. normalis Setchell. 
Edo sf f. vittata Setchell. 
Stipe hollow above, without mucilage ducts. 
7. L. longicruris De la Pylaie. 
The following notes on these species may serve to indicate further 
the specific characters, and also to suggest certain points for further 
investigation. 
A. Dicirata. The four species under this group can generally 
be distinguished by the characters given in the key, at least from 
each other and from all species known with certainty thus far from 
the coast of New England. While the digitate species are common 
north of Cape Cod, they occur rather sparingly to the south of it. 
Additional species are to be looked for along the northernmost 
shores. 
1. L. PLATYMERIS De la Pylaie. There is little to add to the 
description and remarks of Farlow (1881, p. 94) concerning this 
species. It is easily distinguished by its habit, its color, and its size 
from the other digitate species of northern New England, as well 
as by the possession of mucilage ducts in the stipe and hapteres. 
When fresh, or even when soaked out after being rough dried, it 
has a distinctive, penetrating odor quite different from that of any 
other of the New England kelps. It grows in the lower sublittoral, 
and even perhaps in the elittoral zone, epiphytic upon other large 
alge. Its range is from Revere Beach northward. Its habit is well 
