THE MAKINE ALO.T: OF XEW ENGLAND. 159 



a layer of lar^e roiiiuli5>li-aii';:ular cells anil a cortical layer of smaller 

 cells; tetraspores zoiiate, scattered, immersed in the cortex; eysto- 

 carps immersed in tlic iVtuid, and projecting at one side, opening by a 

 distinct carpostome, inclosing t n ft s of spores arranged in short, dense 

 fdaments, snrronnding a globose, cellular, central placenta, connected by 

 filamentous bands with a plexus of the axial lilaments which surrounds 

 the sporiferous mass. 



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

 fined to Australia, divided hy A«:ardh into two 8ul>gouera, in one of which the frond is 

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

 division, and the frond resembles closely that of Cifntoclonium purpuraiivenfi, and tho 

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

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

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

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



R. TENERA, Ag. [Gigartina tenera, J. Ag., Symb. — SoUeria chordalis, 

 narv. (non Ag.), Xer. Am. Bor., Tart II, p. 121, PI. 23 a.— lihabdonia 

 teneraj J. Ag., Spec. — /?. Bailey i, Ilarv. 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 l)y a small disk, 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 ; 

 tetrasi)ores zonate, scattered in the cortex ; cystocarps numerous, 

 immersed, but projecting at one side. 



In warm, quiet bays, in shallow water. 



(Jommou from Cape Cod southward ; Goose Cove, Gloucester, Mass., 



w.a.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 bo mistaken for any other plant, except possibly for a largo form of 

 Cystodonium purpiirascens. The procaq)S 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 fashion, and makes its way to the surface, reminding one of the trichogynes of 

 Hahjmenia Ugulata, figured by Bornet. The section of the cystocarp given by Harvey 

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

 ity, as supposed by Harvey, but has a distinct carj>ostome ; nor are the spores pyri- 

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

 ^•'aments. 



