THE GREEN ALGAE OF NORTH AMERICA 85 



The fronds are often so little branched that one finds an un- 

 branched filament several cm. long : the general appearance is 

 then much that of a marine Chaetomorpha with short swollen 

 cells and thick wall. Its nearest relative would seem to be 

 C. insignis, but C. monilifonnis has much shorter and more 

 uioniliform cells and thicker wall. If C. frada is to be taken 

 to include all non-attached species outside the subgenus Aega- 

 gropila, the present form should be included in it as a variety ; 

 but to include in C. frada, C. insignis, C. oligodona and the 

 present form, would make C. frada altogether more cumbrous 

 and unsatisfactory than it is now ; it is already bad enough. 



Page 367, after description of the genus BOODLE A, add, 



B. SIAMENSIS Reinbold, 1901, p. 107; in Weber, 1913, p. 68, 

 fig. ii ; Borgesen, 1913, p. 49, figs. 34-36. Somewhat intricate 

 and spongy ; main filaments rather distantly branched, branches 

 densely and divaricately branching in all directions ; ramuli 

 here and there adherent by tenacula on their obtuse tips ; 

 length of cells variable, in main filaments up to 20 diam. ; diam. 

 of main filaments 160-200 p, rarely 300 p., ramuli 70-100 /*. Vir- 

 gin Islands. Eastern Asia. 



Cancel all relating to B. COMPOSITA. 



After description of the genus DICTYOSPHAERIA, add, 



KEY TO THE SPECIES OF DICTYOSPHAERIA. 

 i. Frond hollow ; interior of cell wall without acicular projections. 



i. D.favulosa. 

 i. Frond solid; acicular projections within the cells. 



2. D. van Bosseae. 



After description of D. FAVULOSA, add, 



2. D. VAN BOSSEAE Borgesen, 1912, p. 256, figs. 7-9 ; 1913, 

 P- 39. fig 8 - 2 3~ 2 5- Frond irregularly rounded or hemispherical, 

 solid, cells rounded-polygonal, about one-half mm. diam., with 

 acicular projections from the interior cell wall. Virgin Islands. 



Distinguished from D.favulosa by the always solid frond and 

 usually smaller cells, averaging 500 /* diam., seldom reaching 

 800 /*, while those of D. favulosa average over i mm. D. Vers- 

 luysii of the Malayan Archipelago has a solid thallus, and 

 acicular projections into the cells, but the cells are twice the 

 size of those of D. van Bosseae, and the acicular projections long 

 in proportion. 



