No. 6] NEW MELOBESIEAE. 17 



what diverging, terete or subterete, 1.5 — 2.5 mm. thick, occasionally 

 knotty, and slightly attenuating with rounded ends. 



Another and smaller specimen about 12 cm. in diameter and 

 5 cm. thick was also collected in the same place. It is rather 

 rubbed in the part turning upwards. 



In structure the species stands near G. strictum. On a me- 

 dian vertical section the cells of the pith layer are frequently 

 IV2 — "272 times longer than broad, or 25 — 40 <j. long and 12 — 20 

 I broad, most often with rather thick walls. In the rather vigorously 

 developed perithallic layer the cells are square or more or less 

 vertically elongated, however rather irregular in size, frequently 

 12 — 25 [J- long and 12 — 18 fi broad, and here are to be found 

 rather numerous large cells considered to be heterocysts. 



A small specimen 4 — 5 cm. in diameter also from Bermuda 

 (herb. Farlow, no. XIX) seems to belong to the same species. 

 It is more irregular and the branches are more diverging than fre- 

 quently in the typical form of the species, upwards now and then 

 compressed and somewhat approaching a specimen from the same 

 place delineated by Nelson and Dun can, Hist. Corall. pl. 27, 

 fig. 10. 1 ) It al most fully accords in structure with the present 

 species, and is probably to be regarded as a form of it, but also 

 this unfortunately being steril. 



Still another, small and fragmentary, somewhat stunted speci- 

 men from Bermuda (herb. Farlow, no. XVII) is nearly connected 

 in habit with the typical form, but in structure it somewhat ap- 

 proaches O. strictum, with a little longer cells with thinner walls 

 than frequently in the present species. 



A specimen from Florida, collected by A. Agassiz (herb. 

 Farlow, no. XXIII) stands very near the present species, but I 

 am not sure whether it is really to be considered a denominated 

 form or perhaps a separate species. It has almost the shape of a 

 low bush about 5 cm. high and 5—6 cm. in diameter, with less 

 crowded or somewhat spreading branches, here and there with 



x ) Nelson and Dun can, On some Points in the Histology of certain Specie 

 of Corallinaceae. Trans. Linn. Soc. Ser. 2. Bot. Vol. 1, p. 197. London 1876 



