1900] Collins, — New England species of Dictyosiphon 163 
Frond repeatedly branched, 
All branches nearly the same size as the main stem. 
Branches not contracted at the base, D. Aippuroides (Lyng.) Kuetz. 
Branches contracted at the base, 
D. hippuroides var, fragilis (Harv.) Kjellm. 
Branches of successive orders smaller and smaller, the ultimate very slender, 
All except the oldest parts beset with uniformly short ramuli, 
D. hispidus Kjellman. 
No definite short ramuli; branches not contracted at base, 
D. foeniculaceus ( Huds.) Grev. 
No definite short ramuli; branches contracted at base, 
D. foeniculaceus var. Americanus Collins 
It will be noticed that no account has been made of color, although 
nearly all descriptions speak of D. Aippuroides as being dark brown, 
D. foeniculaceus and D. hispidus light brown. The writer's experi- 
ence is that in the living plant age and exposure have more influence 
than have specific differences ; while in the dried specimens the man- 
ner of preparation may make more difference than anything else. 
Altogether the most common form in Europe is D. foeniculaceus, 
the type of the genus; but in New England it seems to be not very 
abundant, at least in its typical form. The main stem bears numer- 
ous alternate branches, each bearing branches of the second order, 
followed by third and other orders, each order being more slender 
than the preceding, the ultimate very fine. Occasionally the main 
stem and some of the larger branches are hollow, otherwise all are 
solid. | 
In Southern New England the typical form is seldom found, but 
its place is taken by what appears to be an undescribed variety, for 
which I propose the name var. Americanus. ‘The contracted bases 
of the branches, the often longitudinally seriate cortical cells, and the 
sporangia frequently in groups, show a tendency to the subgenus 
Coilonema, while the size of the plant, the branches of several orders 
growing successively more slender, agree with typical D. foeniculaceus. 
In habit it resembles Striaria attenuata, Grev., more than it does 
typical D. foeniculaceus. ‘The northernmost point at which it has 
been found is at Weymouth, Mass. (F. S. C.), in the warm water col- 
ony established there. It is the common Dictyosiphon at Newport, 
R. I. (Mrs. W. C. Simmons), and at Bridgeport, Conn. (Isaac Hol- 
den). South of New England it extends at least as far as Atlantic 
City, N. J. (S. R. Morse). It occurs chiefly on Phyllitis fascia (Fl. 
Dan.) Kuetz., in less frequency on Scytosiphon lomentarius (Lyng.) 
Ag., and occasionally on other algae; it is found chiefly in spring. 
