No. 6] NEW MELOBESIEAE. 15 



ded, partly vertically elongated, 12 — 25 /->- long and 12—20 \i 

 broad. Besides are here to be found more or less numerous large 

 cells which are considered to be heterocysts. 



Although the specimen is steril I do not hesitate to adopt it 

 as a new species, but I am not certain whether it in fact is refer- 

 rible to Goniolitlion or Lithophyllum (Lépidomorphum). However, 

 I am most inclined to refer it to the former genus, as heterocysts 

 are present. Such are commonly to be found in the said genus, 

 but hitherto at least never met with in Lithophyllum, nor in Li- 

 thothamnion. The species stands nearest to G. frutescens, which 

 it approaches especially in structure. 



The present species is with certainty only known from Flo- 

 rida, A. Agassiz in herb. F ar lo w, no. XX. 



Some fragments of a steril specimen gathered in Bahamas, 

 herb. Far lo w, no. XXIV, seem however to belong to the same 

 species. The branches are more diverging and on the whole more 

 irregular than in any part of the type, though nearly allied to 

 those in the lower part of the latter and, therefore, probably being 

 fragments of a younger specimen of the species in question. 



G.? intermedium Fosl. mscr. 



Thallus forming almost obpyramidal masses of råtner erect, 

 crowded, subdichotomously divided branches with short axes not 

 curved or slightly so, rather anastomosing, with small and wart- 

 like or longer and branch-like side branches, the latter sometimes 

 issuing at nearly right angles. Branches l l / 2 — 2 mm. thick, terete 

 or subcompressed, slightly attenuating upwards or not, with obtuse 

 or almost truncate ends occasionally depressed in the centre. 



The only specimen hitherto seen is 6 cm. high by a diameter 

 in the thickest part of 3 — 4 cm. 



On a median longitudinal section of the upper part of a branch 

 the cells of the pith layer are l 1 ^ — 3 times longer than broad, or 

 25 — 38 ij. long and 10 — 18 p broad, with rather thin walls. In the 

 very feebly developed perithallic layer occur scattered heterocysts. 



The said specimen is steril, but notwithstanding this I venture 

 to consider it specifically distinct from G. strictum, to which it 



