78 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



A genus comprising eight described species, several of which are undoubtedly merely 

 forms of the common and widely diffused C. vcrticillatus, whose structure is minutely 

 described by Pringsheim, 1. c. The term leaves is applied by Pringsheim to the sec- 

 ondary branches. He considers the branching of the axis to be monopodial. The 

 sporangia are produced in the winter months, the two kinds on separate plants or 

 sometimes together. 



0. verticillatus, Ag. ; Phyc. Brit., PI. 33; Pringsheim, L c, Pis. 1-7. 



Fronds four to ten inches high, slender, subdichotonious, secondary 

 branches distinctly whoiied, falcate, acute at apex, attenuate at base, 

 furnished externally with a few spine-like branchlets ; hairs numerous ; 

 unilocular sporangia globose, plurilocular sporangia irregularly ellip- 

 soidal, borne on short pedicels on small special branches, which grow 

 from the axis between the insertions of the secondary branches. 



Var. SPONGIOSUS. (Cladostephus spongiosus, Ag.; Phyc. Brit., PI. 38.) 



Fronds more compact, whorls approximate, indistinct, secondary 

 branches usually destitute of hairs and spine-like branchlets. 



On stones in pools and below low- water mark. 



Newport, R. I. ; Orient, L. Lj Martha's Vineyard; Cape Ann, Mass.; 

 Europe. 



A plant at once recognized by its resemblance to a small Ceratophyllum. Rather 

 common in several places south of Cape Cod, but seldom seen on the northern coast. 

 It prefers somewhat exposed shores, and occurs at considerable depths. Although the 

 close resemblance between C. verticillatus and C. spongiosus has long been noticed, the 

 two species have generally been considered distinct. Geyler says that C. spongiosus is 

 characterized by the absence of hairs aud the external spines on the branches. Al- 

 though this is in general true, one not unfrequently finds hairs and small spines on 

 some of the branches, and C. spongiosus is evidently merely a variety of C. verticillatus. 

 Nor is it the case, as some have supposed, that the verticillate form is confined to 

 deeper water, while the spongiose form is found in tide-pools and near low-water mark. 



Family MYRIONEME^. 



Fronds minute, forming spots or thin expansions on other algse, con- 

 sisting of prostrate filaments united into a horizontal membrane, from 

 which rise short vertical filaments, between which are borne the sporan- 

 gia; unilocular and pluriocular sporangia as in Ectocarpece. 



MYBIONEMA, Grev. 



(From fivpiog, numberless, and vrj/ia, a thread.) 



Fronds olive-brown, forming thin expansions on other algae, composed 

 of a horizontal layer of cells lying on the substratum, from which arise 

 very numerous vertical filaments, closely packed together; unilocular 

 and plurilocular sporangia between the vertical filaments, either sessile 

 on the horizontal layer or on short pedicels; hairs arising from hori- 

 zontal layer ; growth peripheral. 



