THE MARINE ALG/E OF NEW ENGLAND. 159 



a layer of large roundish-angular cells and a cortical layer of smaller 

 cells ; tetraspores zonate, scattered, immersed in the cortex ; cysto- 

 carps immersed in the frond, and projecting at one side, opening by a 

 distinct carpostome, inclosing tufts of spores arranged in short, dense 

 filaments, surrounding a globose, cellular, central placenta, connected by 

 filamentous bands with a plexus of the axial filaments which surrounds 

 the sporiferous mass. 



A genus comprising from fifteen to twenty species, the greater part of which are con- 

 fined to Australia, divided by Agardh into two subgenera, in one of which the frond is 

 cylindrical and in tbe other constricted at intervals. Our species belongs to the first 

 division, and the frond resembles closely that of Cystoclonium purpurascens, and the 

 same is true of the tetraspores. The cystocarps are large, and project on one side. 

 The genus is placed by Agardh near Solieria, but in that genus the spores are placed 

 around a very large central carpogenic cell, while in Ehabdonia they are attached to a 

 large, solid, central placenta formed of cells. The placenta is attached to the walls of 

 the cystocarp by numerous bands of interwoven filaments, between which are the 

 sporiferous masses, which consist at maturity of short filaments, whose cells are changed 

 into spores, which are not held together by a gelatinous envelope as in Champia. 



E. tenera, Ag. (Gigartina tenera, J. Ag., Symb. — Solieria chordalis, 

 Harv. (non Ag.), Ner. Am. Bor., Part II, p. 121, PI. 23 a. — Rhabdonia 

 tenera, J. Ag., Spec. — R. Bailcyi, Harv. MSS., Am. Journ. Science, Vol. 

 VI, p. 39.) PI. XIV, Fig. 2. 



Fronds deep red, from six inches to a foot and a half long, cylindrical, 

 attached by a small dish, simple below, above densely branched, alter- 

 nately decompound, branches long, virgate, erect, tapering at the base 

 and apex, and furnished with numerous, linear, fusiform branchlets; 

 tetraspores zonate, scattered in the cortex; cystocarps numerous, 

 immersed, but projecting at one side. 



In warm, quiet bays, in shallow water. 



Common from Cape Cod southward ; Goose Cove, Gloucester, Mass., 

 W. G. F. 



A characteristic species of Long Island Sound, and only known in one locality north 

 of Cape Cod, but extending southward to the West Indies. It forms beautiful tufts 

 often two feet long, in muddy places around wharves and in sheltered places, and is 

 not likely to be mistaken for any other plant, except possibly for a large form of 

 Cystoclonium purpurascens. The procarps consist of three cells, and from the inner- 

 most or that nearest the axis grows a long trichogyne, which curves round in a tor- 

 tuous fasnion, and makes its way to the surface, reminding one of the trichogynes of 

 Halymenia llgulata, figured by Bornct. The section of the cystocarp given by Harvey 

 in the Nereis does not pass through the center, and the cystocarp is not a closed cav- 

 ity, as supposed by Harvey, but has a distiuct carpostome ; nor are the spores pyri- 

 form and attached to separate pedicels, but they are formed from the cells of short 

 filaments. 



