506 BULLETIN OF THE BUREAU OF FISHERIES. 
The genus is distinguished from Polysiphonia by the persistent trichoblasts and the 
consequent characteristic habit. It is distinguished from Dasya by its monopodial 
growth. 
Brongniartella mucronata (Harvey) Schmitz. Pl. CIX, fig. 4. 
Dasya mucronata, Harvey, 1853, D. 63. 
Brongniartella mucronata, Schmitz, 18938, p. 218. 
Brongniartella mucronata, De Toni, 1903, D. 1012. 
A. A. B. Ex. No. 2 (Dasya mucronata). 
P. B.-A. No. 247 (Dasya mucronata). 
Fronds robust, rather terete, 3 to 20 cm. tall, about 0.5 to 1 mm. in diameter in main stems, one or 
more arising from a basal, disklike expansion, branching usually lateral and distant, sometimes dicho- 
tomous, lower portions of the main stem and larger branches naked, smaller branches and apical por- 
tions of larger ones densely covered by monosiphonous, dichotomous, rather rigid, spreading trichoblasts 
going out on all sides from the cortical layer and mucronate at the apices; pericentral cells five, seg- 
ments not conspicuous, about 0.5 diameter long in the main stem and larger branches, 1.5 to 2 diam- 
eters in smaller branches, covered throughout by a dense cortex; tetrasporangia in somewhat spiral row 
among the cortical cells of scarcely altered branchlets; antheridia and cystocarps unknown; texture 
firm, cartilaginous; color of the stem and branches dull, brownish-red, that of the trichoblasts usually 
brighter, rosy red. 
Florida and West Indies. 
Occasional on Bogue Beach, Beaufort, N. C., summer and autumn, usually sterile, rarely tetra- 
sporic, few specimens, 3 to 6 cm. tall, dredged on coral reef offshore, May, 1907, and July, rors. 
This species is easily recognized. Neither the species nor the genus is known elsewhere on our 
coast north of Florida. 
Genus 5. Bostrychia Montagne. 
Bostrychia, Montagne, 1838, p. 39. 
Frond usually creeping with erect branches, less often erect, more or less flattened, 
sometimes apparently terete, branching usually distichous and alternate, sometimes 
somewhat dichotomous or radial, longer branches bearing two lateral rows of short 
branches, usually of limited growth, ultimate branchlets simple or branched, often 
monosiphonous; structure cellular, with a circle of 4 to 11 pericentral cells, the number 
often varying from base to apex, naked or sooner or later inclosed by one or more layers 
of cortical cells, the segments sometimes becoming indistinct from the transverse and 
longitudinal division of the pericentral cells, apical growth monopodial, apices often 
monosiphonous, often bent or inrolled, apical cell alternately transversely and obliquely 
divided; tetrasporangia occurring in ultimate, more or less transformed, stichidiumlike 
branchlets, arising in whorls of 4 to 6 from the pericentral cells, triangularly divided, 
more or less covered by a layer of small cover cells; antheridia composed of a larger or 
smaller number of the middle, thickened segments of simple, cylindrical branchlets, the 
spermatangia occurring in a dense layer over the surface; procarps numerous in single 
or double rows, embedded in the cortex of slightly thickened branchlets; cystocarps 
broad-ovate, conspicuous, usually occurring singly, apparently at the apices of branch- 
lets, pericarp fairly thin, opening by a conspicuous terminal carpostome, gonimoblast 
composed of compressed or more elongated dichotomous-fastigiate filaments, forming 
single long pear-shaped or club-shaped carpospores from their terminal segments. 
About 30 species, mostly in warm regions, usually in brackish water at the mouths 
of rivers, often extending into fresh water, some species known only in fresh water. 
