504 BULLETIN OF THE BUREAU OF FISHERIES. 
above. branches sometimes elongated and somewhat zigzag, gradually tapering, and divided into numer- 
ous fine branchlets toward the apices, branchlets arising laterally, often forming dense fastigiate tufts, 
especially toward the apices; pericentral cells six to eight, usually six, rarely five, segments 1 diameter 
long or less below, 2 to 3 diameters above, no cortex; tetrasporangia in somewhat torulose series in the 
branchlets; antheridia linear-oblong, acute at apices; cystocarps broad-ovate, toward the apices of small 
branches; color dark brownish or blackish purple. 
Warm and temperate North Atlantic. 
Occasionally abundant on buoys, Beaufort, N. C., July to September, sometimes fruiting. One mass 
on buoy in Sound, Port Royal, S. C., and very abundant on Gracilaria multipartila var. angustissima 
at mouth of one creek, August, 1909. 
Fig. 36.—Chondria littoralis, apex of branch, X 4o. Fig. 41.—Polysibhonia spp., cross sections of stems. A. 
Fig. 37.—Chondria littoralis (?), apex of branch, X 4o. P. harveyit.. B. P. denudata. C. P. nigrescens. X 40. 
Fig. 38.—Chondria dasyphylla, apex of branch, X 4o. Fig. 42.—Spermothamnion investiens, partly divided tetra- 
Fig. 39.—Chondria dasyphylla, anthreidium, X 157. sporangium producing vegetative filament, X 263. 
Fig. 40.—Chondria dasyphylla, young plants, X 157. Fig. 43.—Griffithsia sp. X 40. 
This is the only determinable species having six pericentral cells observed in this region. The 
habit, while more or less dense, is characteristic, and the determination is less difficult than in most 
species of the genus. The plants growing on the buoys are small (2 to 4cm.), while those from the creek 
at Port Royal are 6 to 15 cm. tall. According to Harvey, this species is very abundant in the harbor of 
Charleston, S. C., during January and February. 
4. Polysiphonia nigrescens (Hudson) Greville. Fig. 41C; Pl. CIX, fig. 3. 
Conferva nigrescens, Hudson, 1778, p. 602. 
Polysiphonia nigrescens, Greville, in Hooker, 1833, p. 322. 
Polysiphonia nigrescens, Harvey, 1853, Pp. 49. 
Polysiphonia nigrescens, Farlow, 1882, p. 174. 
Polysiphonia nigrescens, De Toni, 1903, Pp. 940. 
Fronds forming erect* tufts 4 to 30 cm. tall, setaceous and rather rigid below, flaccid and much 
branched above, branching pinnate, alternate, decompound, rather regular, young branches usually 
