104 Rhodora [May 
of DuRoi. Dippel gives a good characterization of our present variety 
as S. alba latifolia; while Koch goes a step farther and considers 
them all three distinct species. i 
CORNELL UNIVERSITY. 
CHLOROCYSTIS COHNII ON THE MASSACHUSETTS CoasT.— There was 
one genus omitted from Mr. Collins’ valuable list of marine algae in the 
February RHopona, which should be added in order to make it more 
complete. I refer to the grass-green unicellular alga, Chlorocystis 
Cohnii (Wright) Reinh., which was first collected by me in February, 
1897, growing on Enteromorpha fronds, along the shore, at Lynn, 
Mass. ‘This species, which is quite common throughout the year at 
the locality noted, has not been previously reported from this country, 
and has been only occasionally found abroad. Wright first discovered 
it off the coast of Ireland in 1877. Seven years later Lagerheim col- 
lected it on Swedish shores, and the following season Reinhard came 
across the plant while studying the flora of the Black Sea. Since 
then de Wildman secured specimens on the coast of France, and in 
1894 Rosenvinge reported it from Greenland. All of these observers 
found the plant growing endophytically on various marine algae ; but 
the material from Lynn showed CA/orocystis Cohnii to be epiphytic in 
its habit quite as often as endophytic. "Thus far Enteromorpha is the 
only host for America.—G. T. Moopr, Dartmouth College. 
VARIATIONS OF ILEX VERTICILLALIA. 
B. L. ROBINSON. 
Our common black alder has long been recognized as a polymor- 
phous species, and attempts have from time to time been made to 
distinguish and characterize its varieties. These, so far as described, 
have been based chiefly upon the size, shape, texture, and pubescence 
of the leaves, features which show too much tendency toward indepen- 
dent variation to yield very satisfactory combinations of characters. 
Nevertheless, of these varieties the following forms (including the 
typical one), which were clearly recognized, although not fully pub- 
lished by Torrey & Gray, are sufficiently characteristic to merit a place 
in descriptive floras. It will be seen from the notes below that two 
