THE MARINE ALG.E OF NEW ENGLAND. 169 



K. stjbfusoa, Ag. ; Phyc. Brit., PI. 264. 



Exs. — Alg. Am. Bor., Farlow, Anderson & Eaton, No. 55. 



Fronds six inches to a foot and a half long, terete, pinnately decom- 

 pound, branches virgate, lower branchlets patent, subulate, the upper 

 iascicultito-corymbose; tetraspores prominent in subtorulose branchlets ; 

 cystocarps sessile, ovato-globose. 



Yar. gracilioe, J. Ag. (Ehodomela gracilis, Harv., Ner. Am. Bor., 

 Part H, PL 13 c.) 



Fronds slender ; tetrasporic branches distinctly torulose. 



In deep tide-pools and at a depth of several fathoms. 



Throughout our whole limits j Europe. 



A species which varies very much with the time of year and the place of growth. 

 It is usually common in the spring months, when it is often washed ashore, and in the 

 summer and autumn it is occasionally found, especially in dredging, in a denuded 

 form, nothing remaining but the older branches, which are perennial and which give 

 rise the following season to rather delicate new branches. As usually seen on Cape Ann 

 the fronds are short, robust, and dark colored, even iu early spring, while at "Wood's 

 Holl and in Long Island Sound the common spring form is much attenuated, delicate, 

 and of a brighter red color, forming the Ehodomela Rodhei of the Nereis. In spite of 

 the difference in aspect, the extreme forms are connected by numerous transitional 

 stages which make it impossible to admit a specihc distinction. By Agardh R. Rochei 

 is considered to be the spring form of the typical R. subfusca, but we are more inclined 

 to regard it as the young of the var. gracilior, which is more common south of Cape 

 Cod, the type occurring northward. The species does not adhere well to paper. 



POLYSIPHONIA, Grev. 



(From TroXvg , many, and ovpuv, a tube. ) 



Fronds filamentous or subcompressed, distichously or irregularly 

 branching, formed of a monosiphonous axis and several (4-20) siphons, 

 often with secondary siphons, and either naked or with a cortical layer 

 of irregular cells, furnished with numerous tufts of hyaline, monosipho- 

 nous, dichotomous filaments ; antheridia lanceolate in outline, borne on 

 the dichotomous filaments ; tetraspores tripartite, in one, rarely in two, 

 rows, in the slightly altered upper branches ; cystocarps ovato-globose 

 or urceolate ; spores pyriform, on short pedicels borne around a basal 

 carpogenic cell. 



The largest genus of Florideoe, of which more than two hundred species have been 

 described, but not all of which can be considered valid. They abound in all parts of 

 the world, especially in warm, shallow waters. Some are perennial, but the majority 

 are annual and disappear during the winter. They are easily recognized at sight by 

 the structure of the frond and the tetraspores, which are almost always in a single row 

 in the upper branches, rarely in a double row, and not in swollen special branches or 

 Btichidia, as in Bostryehia, which is nearly related to Polysiphonia. The growth is from 

 a single apical cell, from which is formed a monosiphonous axis. By tangential di- 

 visions of the upper cells there is formed a number of peripheral cells and a central 



