THE MARINK ALCJ.E OF NKW KNCJLAND. 187 



Fronds small, tufteil, foinposi'd of a (It'iisc l»asal poitinn and an 



DUttT portion conqmsod of free lilanieuts '-^S 



Fronds tnbular, nnbranrhod -*^ 



Fronds filamentous '51 



Fronds njonibranaceons, ('\j)an(U'd U 



J7. Kronds (U-nst'ly part'ncliyniatous ilmtn^^liont, frnit in external 



spots . -. Ralfsia. 



Fronds minute, tliin, fornu'd of a basal horizontal layer of eells and 

 short vertical filaments, between which the sporan;;ia are borne. 



Mi/rioncma. 



2S. Free tilaments all alike Mi/riactis.* 



Free lilaments of two kinds, one short and the other exserted. 



l^lochistea, 



L"J. I'ronds simple, liollow throughout, substance thin 30 



Fronds simple, cylindrical, somewhat cartilaginous, witii numerous 



diaphragms Chorda. 



Fronds branching, substance thin, sporangia large, arranged iu 



transverse lines Striaria. 



:iO. Sporangia densely coveiing the surface ^Scytosiphon. 



Sporangia external in scattered spots Asperococcus. 



31. Fronds capillary, branching, formed of single rows of cells (mono- 



siphonous) Fctncarpus. 



Fronds cylindrical, solid or occasionally becoming partially hollow 



with age 32 



;>2. Fronds slimy, composed of an axial layer of elongated filaments 



and a distinct cortical layer of short, horizontal tilaments 33 



Fronds composed of elongated internal cells, which become smaller 



and polygonal at the surface 35 



Fronds, at least in the younger portions, formed of cells of nearly 

 uniform length, arranged in transverse bands, without any proper 

 cortical layer 38 



33. Fronds tough and dense Chordaria. 



Fronds soft and flaccid 3J: 



34. Outer cells of cortex producing plurilocular sporangia . . C(isf(i(/nei(. 

 Outer cells of cortex not i)roducing plurilocular sporangia. J/cvo^/om. 



35. Fronds traversed by a central filament formed of large cylindrical 



cells placed end to end 30 



Fronds destitute of «listinct axile fdament . - 37 



30. Sporangia in branching, monosiphonous filaments, which form tufted 



whorls on the l)ranches ArthrocUidia. 



Sporangia inconsi)icuous, formed from the cortical cells -7>r«/«a/T.s7m. 

 37. Si)oningia globose, prominent in the cortical layer Viciyosiphon. 



• When reference is made in Myriactis and the following; genera of I'iKrofiporeee to 

 free external filaments, it shotiM be nnderntood that only filaments whowe cells contain 

 coloring matter an* meant, and that no account is to be taken of the numerous hyaline 

 hairs with which most of the species oi Phaoapona arc covered at certain seasons. 



