1901] Collins, — Notes on Algae, — III 133 
produced zoospores plentifully. Probably it occurs all along the 
coast, but it is so inconspicuous that unless one is looking for it, 
it will hardly be found. 
Plectonema Nostocorum Bornet was found in the gelatine of a 
small Nostoc, growing in a watering trough by the side of the road 
from Seal Harbor to Jordan Pond, Mount Desert, Maine, July 16, 
1900. It is a very minute plant, the filaments being only 1 to 1.5 u 
diameter, is common in Europe in connection with various gelatin- 
ous algae, and will probably be found equally abundant in this 
country. It is described and figured in Gomont, Monographie des 
Oscillariées, p. 122, pl. I, fig. rr. 
Ectocarpus fasciculatus var. abbreviatus (Kuetz.) Sauv. seems to be 
common on Laminariaceae from Boston north. It usually covers 
the older part of the lamina of the host with a dense coating, the 
fronds seldom over a centimeter high. The fructification is like 
the type, except that the sporangia are often clustered, and are often 
found, apparently proliferous, on the main stem, sometimes at the 
very base; the branching is quite irregular. 
Elachista Chondri Aresch., Obs. Phyc., part 3, p. 17, pl. II, fig. 2, 
occurred at Ochre Point, Newport, R. I., May 26, 1900, growing on 
Chondrus crispus (L.) Stack. near low water mark, at a point exposed 
to the surf. In general appearance it is not unlike Æ. fucicola 
(Velley) Fries, common everywhere on Ascophyllum nodosum, and 
occasionally on other plants. Most of the species of Elachista seem 
to be limited to one or a few host plants each, and this species was 
found by its author growing on Chondrus crispus and Furcellaria 
Jastigiata (Huds.) Lamour., on the coast of Sweden. ‘The latter host 
has not been found in America, but the Chondrus is very common 
along the whole New England coast. Possibly it may be found 
that Æ. Chondri is not rare, but certainly it is not common; the 
writer has for two or three years given some attention to Chondrus, 
in regard to the different organs of fructification, and would hardly 
have overlooked a plant like EZ. Chondri. 
Actinococcus aggregatus Schmitz, Flora, p. 385, 1893, occurs on 
Gymnogongrus Griffithsiae (Vurn.) Mart., growing at low water mark 
on the beach at Portsmouth, Rhode Island, near Wood Island Park : 
it was fairly abundant in June, r9oo. The genus Actinococcus is 
made up of several species, each formerly supposed to be the tetra- 
sporic fruit of some alga, which is now considered merely the host 
