THE MAUIXi: ALG.E OF NEW ENGLAND. 191 



73. Fronds loii;^", cylindrical, densely clothed with lake-red hairs. . Dasj/a. 

 Fronds i>nrple or dark red, occasionally blackish, sui)erlicial cells 



either throu<i:hout or at least in the youn^ branches arranged in 



transverse bands 74 



Fronds dark red, ninch br.inched, rather robnst, sui)erticial cells 

 small, irregularly i)laced Uhoilomela. 



74. Tetras])ores borne in the younger branches rolysiphon'ui. 



Tetras])ores borne in swollen, pod-like branches (stichidia). 



Hoxtnjvltin. 



75. Fronds cartilaginous, dense, spores immersed in the substance of 



frond 70 



Fronds delicate or somewhat coriaceous 71) 



Fronds gelatinous, livid purple, comi)osed of a single layer of cells, 



spores in marginal bands or spots Vorphyra. 



70. Fronds formed internally of numerous anastomosuig fdaments which 



divide corymbosely at the surface 77 



Fronds formed of roundish angular cells throughout 78 



77. Fronds i)lane or slightly channelled Chondrus. 



Fronds beset with small papilhe, in which the spores are borne. 



Gigartina, 



78. Fronds with a prominent stipe, which passes into a proliferous la- 



mina, cystocarps external, globose rhyllophora. 



Fronds linear, regularly dichotomous, cystocarps immersed. 



Gymnogongrxis. 



70. :Midrib present 80 



^lidrib wanting 82 



SO. Fronds rosy red, leaf-like 81 



Fronds dark brownish purple, narrow, dentate, midrib scarcely dis- 

 tinct Odonthalia. 



81. Tetraspores in spots on the fronds, lateral veins usually present. 



Dclesseria. 



Lateral veins wanting, tetraspores in thickened portions of the 



fronds GrinnelUa. 



82. Fronds narrow, much divided 84 



Fronds palmately or dichotomously divided 83 



83. Fronds deep red, broadly palmate, margins proliferous, tetrasj)ores 



cruciate in i)atches lihodymcnia. 



Fronds dark red, margins ciliate, tetraspoies zonatc.. IthodophyUis. 

 Fronds dark ])urple, deei)ly divided, tetraspores scattered, cruciate. 



GracUaria. 



84. Branches alternately secund in threes or fours, the lowest undivided 



and spine-like, the rest pinnate rUnamium. 



Fronds subtlabellate, upper divisions divaricately toothed. A^z/Aora. 



