508 BULLETIN OF THE BUREAU OF FISHERIES. 



Fronds forming a very fine capillary mat or fringe, composed of creeping filaments with short 

 erect branches, primary filaments decompound, erect, short branches, slender, curved, tapering slightly 

 toward the apices, borne in two rows, coming to lie approximately in one row; pericentral cells 8 to 10, 

 segments 1.5 to 2 diameters long in the primary filaments, about i diameter long in the branchlets; 

 tetrasporangia occurring singly in single, straight, unbroken rows of 20 to 30 in erect, short branches; 

 antheridia often borne on every segment for about one-third the length of the branch, beginning about 

 the middle and extending toward the apex; cystocarps usually borne singly on short stalks; texture 

 velvety; color purplish red. 



Florida and West Indies; Mediterranean. 



Abundant on Fort Macon and Shackleford jetties, Beaufort, N. C., throughout the year, on other 

 alga?, especially Padina vickersice, and sometimes on the Polyzoan Bugula turrita, fruiting August and 

 September, probably throughout the summer and autumn. Fairly abundant on Dictyota dichotoma, in 

 sound near inlet, Wrightsville Beach, N. C., July, 1909. Fairly abundant on shells -and other algae, in 

 sound near inlet, Pawleys Island, near Georgetown, S. C., August, 1909. 



This species will not be mistaken for any other occurring in this region, being easily recognized by 

 its appearance of a creeping Polysiphonia, forming purplish red, velvety mats or fringes composed of 

 horizontal filaments with upright branches. The species is dioecious. Often all the filaments observed 

 on a single specimen of the host were either sexual (both male and female) or tetrasporic, but sometimes 

 both tetrasporic and sexual plants occurred together. 



This is the northern known limit of the species and of the genus. 



Genus 7. Dasya Agardh. 



Dasya, Agardh, 1824, p. XXXIV. 



Frond erect, terete, radially constructed, laterally and radially somewhat irregu- 

 larly branched, long and short branches intermixed; structure cellular' or filamentous- 

 cellular, with a circle of five (very rarely four) pericentral cells, naked or inclosed by a 

 more or less dense rhizoidal cortex, apical growth sympodial, the entire frond or the 

 younger parts densely covered by spirally arranged, repeatedly forked, colored tricho- 

 blasts; tetrasporangia in whorls (usually of five sporangia) at each segment of special 

 lanceolate branchlets (stichidia) arising as young branches of the trichoblasts and 

 attached to these by monosiphonous stalks, covered by special cover cells when young, 

 uncovered when mature, triangularly divided; antheridia arising as branches of the 

 trichoblasts, lanceolate-conical, ending in a sterile apex, borne on a monosiphonous 

 stalk; procarps numerous near the growing apices of more or less developed lateral 

 branches; cystocarps ovate-globose or urn-shaped, borne laterally on smaller branches, 

 pericarp rather thin, opening by a conspicuous terminal carpostome, gonimoblast com- 

 posed of dichotomously branched filaments radiating from a basal placenta, forming 

 oval or club-shaped carpospores singly or, rarely, in short chains of two to three spores 

 from their terminal segments. 



Thirty to forty species, in warm seas. 

 Dasya pedicellata Agardh. PI. CX, fig. 2. 



Dasya pedicellata, Agardh, 1824, p. an. 



Dasya elegans, Harvey, 1853, p. 60. 



Dasya elegans, Farlow, 1882, p. 177, pi. is,{ . i. 



Dasya elegans, De Toni, 1903, p. 1201. 



A. A. B. Ex. No. 51 (Dasya elegans). 



P. B.-A. No. 545. Pasc. A, No. XXIII (Dasya elegans). 



Fronds moderately robust, flexuous, terete, 4 to 90 cm. long, about 0.6 to 6 mm. in diameter in 

 main stems, arising singly from a small basal disk, branching lateral, decompound, sparse or profuse, 

 lower portions of the main stem and larger branches naked, smaller branches, and sometimes almost 

 the entire plant, very densely covered by conspicuous, monosiphonous, dichotomous, flaccid tricho- 

 blasts going out on all sides from the cortical layer, not tapering toward the apices; pericentral cells 



