1908] СоШпз,— Genus Pilinia 125 
the cells in a filament increase in diameter from the base to the summit, 
and may reach 6 or 7 м diam. When the terminal cell changes to a 
sporangium, the size is still greater; the normal form of a sporangium 
seems to be pyriform, and the size 20-24 X 10-12 м, but various 
irregular forms are common. ‘The distinction between basal and erect 
filaments is less than in P. Lunatiae, but the sporangia are more clearly 
differentiated. It was found on pebbles on the shore of the “Salt 
Pond,” Eastham, Massachusetts, July, 1907. The pebbles were 
between high and low tide marks, and when the tide was out were 
wet with cold fresh water from a spring. 
P. Reinschii (Wille) nov. comb. Acroblaste spec. Reinsch, Bot. 
Zeit., Vol. XXXVII, p. 361, Pl. III. A, 1878; A. Reinschii Wille in 
Engler & Prantl, Nat. Pflanzenfam., Algen, p. 97, 1890; Collins, 
List, RHopona, Vol. II, p. 43, 1900, as to southern Massachusetts 
localities only; not Collins, Holden & Setchell, P. B.-A., No. 162, 
1896. In this species the basal layer shows the filamentous character 
throughout, even when the filaments are laterally united; often they 
remain practically free. The erect filaments are 5-8 м. diam., and 
may reach a length of 400 or 500 м; they are regularly cylindrical 
except for a slight constriction at the nodes, or less commonly increase 
in size very slightly upwards; in either case the terminal sporangium 
is sharply differentiated from the other cells, ovoid or oblong, 16- 
18 м diam. Sometimes the erect filaments are simple, and it is only 
in such cases that the upper cells are larger than the lower; the dif- 
ference is slight, in any case. Ordinarily the filaments are more or 
less freely branched, and of the same size throughout. The sporan- 
gia are terminal on the main filament or on longer or shorter branches; 
in some cases a branch is developed from the cell below a sporangium, 
pushing the latter to one side, so that it appears to be a lateral growth. 
The spores escape through a terminal opening in the sporangium, 
almost as large as its diameter; after their escape the filament may 
resume its growth, coming up through the persistent empty sporan- 
gium. It is not uncommon to find several empty shells at different 
heights on a long filament. The color is a yellowish, somewhat 
olivaceous green; Heinsch notes its resemblance to small species of 
Ectocarpus. He found it growing on shells of a species of Turri- 
tella, which it covers with a dense coating; and also on pebbles, both 
between tides and in shallow water. The writer has found it on 
other shells, and also on the claws of the spider crab, Libinia canali- 
