10 M. FOSLIE. LI 900 



pressed and flabellate. Conceptacles of sporangia conical, with 

 elongated tip, 500 — 600 ;j. in diameter. . 



The species is muen varying in shape, sometimes with the 

 appearance of a small bush 2 — 4 cm. in height, but developing 

 numerous conceptacles, sometimes forming almost roundish balls 

 up to 10 cm. in diameter, and apparently now and then loosening 

 itself from the substratum. 



In f. typica the branches are terete or subcompressed, subdi- 

 chotomously or rather irregularly divided, sometimes issuing at 

 right or nearly right angles, short or elongated, with rounded or 

 truncate ends. 



In f. flabelliformis especially the upper branches are more or 

 less fan-shaped, with segments up to 10 mm. broad. 



The conceptacles of sporangia are prominent, numerous though 

 seldom crowded, conical, 500—600 jj. in diameter at the base, 

 with an elongated tip, including the latter about 500 /J- high. To- 

 wards maturity the tip falls away and then the conceptacles are 

 subhemispheric or subhemispheric conical. The sporangia are four- 

 parted, 90—110 by 40—50 /*. 



A longitudinal section of a branch does not show any cup- 

 shaped stratification as frequently in other branched species of this 

 group of calcareous Algæ, the inner cells however forming pretty 

 regular radiating rows, frequently P/2 — 2 times longer than broad, 

 or 20—36 by 14 — 18 \i. The perithallic layer is partly rather 

 feebly partly vigorously developed, with almost square or some- 

 what rounded cells, or up to l 1 /^ times longer than broad. Bet- 

 ween the peripheric cells are frequently to be found scattered and 

 rather large cells quite differing from the adjacent ones, which 

 appear to be heterocysts. 



The present species muen approaches O. moluccense in habit, 

 being however coarser, with larger conceptacles and quite different 

 in structure. 



In a longitudinal section of a branch of G. moluccense the 

 pith layer is composed of alternating long and short cells, forming 

 regular radiating row r s. The short cells are frequently twice as 

 long as broad, or 18 — 28 by 7.5 — 11 fi, in the longitudinal direc- 



