212 Rhodora [AucvsT 
from Nahant northward. Forma epiphytica n. f. is abundant from 
Nahant to Portland, Maine, growing on Polysiphonia fastigiata (Roth) 
Grev., or on Ascophyllum nodosum (L.) Le Jolis, the host plant of 
the Polysiphonia. The young fronds are ovate to orbicular in out- 
line, becoming torn and irregular as they grow older ; they are seldom 
over four or five cm. long. On the coast of eastern Maine the form 
seems to pass into the type, but on the Massachusetts coast the two 
are quite distinct. It is a plant of spring and early summer, while 
the type and var. umbilicalis are found throughout the year. The 
plant distributed as P. /aciniata in Phyc. Bor.-Am., No. 235 is forma 
epiphytica. P. leucosticta is a plant of the spring months and of warm 
waters; it has not been found north of Boston. It has been dis- 
tributed as Phyc. Bor.-Am., No. 376. The other three species are 
all northern forms, P. femuissima and P. miniata occurring as far 
south as Nahant, while P. amplissima has been found only at Jones- 
port, Maine, as noted in Ruopora, Vol. IV, p. 177. P. miniata, from 
Newfoundland, has been distributed as Phyc. Bor. Am., No. 377, 
and P. amplissima, from Washington as No. XLIX of the same.! 
It should be noted that Rosenvinge, Grønlands Havalger, p. 827 
includes P. amplissima, P. tenuissima and P. abyssicola, the latter not 
occurring in New England as varieties under P. miniata. Rosen- 
vinge's rule, to include under one species all forms which are con- 
nected by intermediate forms, leads to many such inclusions, where 
other authors see distinct species. As Hus, after careful study, and 
with the approval of Prof. Setchell, keeps them distinct, it has seemed 
best to do so here. 
! P, linearis Grev. with linear fronds 15-20 cm. long, and one half to two cm. 
wide, with distinct stipe and cordate base, has been found by Mr. Isaac Holden 
at St. Johns, Newfoundland, growing in tufts on exposed rocks, and may be 
expected on the Maine coast. Whether it is a distinct species, or a variety of P. 
laciniata is uncertain. 
Vol. 5, no. 55, including pages 177 to 192, was issued 7 July, 1903. 
