THE MARINE ALG.E OF NEW ENGLAND. 83 



Common on al^ie and on sand-covered rocks at low water alongf tlio 

 whole coast. 



Not to bo mistaken lor any o\hcT al.^a on our coast. Tho pjolatinons balls which 

 this species forms are Ibnnd ^rowin^j; in lar;;e quantities at low- water mark, and are 

 fiomctimes called potatoes by the uuromautic dwellers ou the shore. 



Family CIIORDARIE.E. 



Fronds cylindrical, branching, usually gelatinous, with an axis of 

 longitndinal filaments formed of long slender cells, and a cortex com- 

 posed of short, densely packed horizontal filaments formed of subspheri- 

 cal cells; sporangia borne among the cortical lilaments or formed directly 

 from them. 



Fronds tough and elastic, cortical filaments densely united to one an- 

 other _ Chordaria. 



Fronds gelatinous, cortical filaments only adhering loosely to one an- 

 other. 



Ui>per cells of the cortical filaments producing the pliirilocular 



sporangia , . Castagnea. 



Upper cells of cortical filaments not producing sporangia. 



Mesogloia, 



CUOEDARIA, Ag. 



(From chorda, a chord.) 



Fronds olive brown, cartilaginous, filiform, branching; axial layer 

 composed of longitudinally elongated cylindrical cells and smaller wind- 

 ing cells packed closely together in a solid mass; peripheral layer 

 composed of short, simple, horizontal filaments, densely packed together; 

 unilocular sporangia oblong, borne at the base of the peripheral fila- 

 ments (parai^hyses), plurilocular sporangia unknown. 



The distinction between the genera Chordaria and Mesogloia, in the absence of a 

 lcn«»wledge of the development of the fronds, must be quite arbitrary. In the present 

 instance we have considered that the genus Chordaria should be limited to the forms 

 having a tough cartilaginous substance and solid axis, of which we have only one 

 representative, C. flagtlli/ormin. C. divaricata, both in its consistency and the devel- 

 opment of the frond, seems to belong to Hi«ogloia, accepting that genus in an 

 extruded sense as we have done. 



< '. FLAGELLIFOEMIS, Ag.; Phyc. Brit., ri. 3. PI. V, Fig. 2. 



Fronds blackish, solitary or gregarious, attached by a disk, coriaceous, 

 lubricous, one to two fei*t long, filiform, solid, main axis usually undi- 

 vided, furnished with numerous long, subequal, fiagelliform branches, 

 which are given oft* at wide angles, simple or with few, irregidar, soc- 

 on<lary branches; peripheral filaments (paraphyses) few-celled, cylin- 

 drical or slightly club-shaped; unilocular sporangia ovoid or pyriform. 



