430 BULLETIN OF THE BUREAU OF FISHERIES. 
Gomontia polyrhiza (Lagerheim) Bornet and Flahault. Fig. 4. 
Codiolum polyrhizum, Lagerheim, 188s, p. 22, pl. 28. 
Gomontia polyrhiza, Bornet and Flahault, 1888a, p. 163. 
Gomontia polyrhiza, Bornet and Flahault, 1889, p. CLII, pls. 6-8. 
Gomontia polyrhiza, De Toni, 1889, p. 389. 
Gomontia polyrhiza, Collins, 1909, p. 370, pl. ts, f. 135. 
P. B.-A. No. 315. 
Filaments 4 to 8 mic. in diameter; sporangia 30 to 4o mic. in diameter; zoospores of two sorts, one 
10 to 12 by 5 to 6 mic., the other about 5 by 3.5 mic.; development not known; the smaller ones possibly 
gametes(?); aplanospores 4 mic. in diameter. 
Abundant on both coasts of North America; Europe. 
In shells, Pamlico Sound, Ocracoke, N. C., August, 1907. 
Order 8. Siphonales. 
Fronds filiform, usually much branched or interwoven into various forms, usually 
continuous without dissepiments in the vegetative condition, multinucleate, with many 
lens or disk shaped chromatophores. 
The members of this order are, with few exceptions, marine and are mostly confined 
to tropical and warm temperate regions. 
KEY TO FAMILIES. 
a. Frond differentiated into root, stem, and branches of varied form......... 4. CAULERPACE& (p. 434). 
aa. Frond not differentiated into root, stem, and branches... 04:0... 0.0052 e cee cece tees b. 
6. Filaments interwoven to form fronds of definite form..................... 3- CODIACE# (p. 431). 
bb. Filaments branching plumosely, not interwoven.................... 2. BRYOPSIDACE& (p. 431). 
bbb. Filaments branching dichotomously or irregularly, forming indefinite mats 
Sao k dep iGo oR o Act cos Orato cieEn eb dic oth Senge siWs aioe Bechet ofa 1. DERBESIACE (p. 430). 
Family 1. DERBESIACEZ Thuret. 
Vegetative frond mostly unicellular, irregularly or dichotomously branched, forming 
indefinite mats, or consisting of upright branches arising from creeping filaments attached 
to the substratum by short, irregular branches; chromatophores large or small disks, 
each containing 1 to 3 pyrenoids, or lacking these; asexual propagation by means of 
almost spherical zoospores, formed (8 to 20) in sporangia arising as lateral branches of 
definite shape and cut off from the main filaments by cross walls, each zoospore possessing 
a circle of cilia and germinating immediately; sexual reproduction unknown. 
About nine species, all marine, in North America, Europe, and Asia. 
Genus Derbesia Solier. 
Derbesia, Solier, 1847, p. 157. 
Characters of the family. 
About nine species. 
Derbesia turbinata Howe and Hoyt. Pl. CXV, figs, 10-16. 
Derbesia turbinata, Howe and Hoyt, 1916, p. 106, pl. rr, figs. 10-16. 
Derbesia turbinata, Collins, 1918, D. 92. : 
Frond more or less creeping, forming straggling mats 8 to 9 cm. broad (or high?) the basal parts some- 
times here and there resolved into cysts; filaments 16 to 100 mic. (mostly 4o to 55 mic.) in diameter, 
sparingly branched, the branching subdichotomous or more often lateral, the lateral branches usually 
without a basal septum, the others with or without one or two septa above the dichotomy; chloroplasts 
at first orbicular elliptic or ovate, 5 to 7 mic. in diameter, later irregularly confluent and spindle 
shaped; zoosporangia turbinate, broadly obconi-obovoid, broadly pyriform, or pestle shaped, 137 to 
