464 M. FOSLIE. 



Genus ArchaeoUthothamnion (Rothpi.) Fosi.' 



1. A. Schmidtii Fosl. 



Corall. in Schmidt, Fl. Koh Chang, ii. p. 16. 



f. dissita Fosl. mscr. (Plate XXIV. fig. 1). 



Branches rather scattered and up to 3 mm. thick, increasing in thickness upwards. 



Only two specimens were till now known of the t3rpical form of this species, and these 

 so exactly resembled each other, that it is uncertain whether the species shows any tendency 

 to variation. Notwithstanding this, I refer the above form to A. Schmidtii, although it 

 rather differs in habit from the type of the latter. Thus even in an advanced stage the 

 branches are not so crowded as in the typical form, but the crust itself is of about the 

 same thickness. They frequently issue at intervals of 3 — 5 mm., nearly always increasing in 

 thickness upwards, or occasionally with almost spherically thickened ends, and up to about 

 8 mm. long. In addition they are most often thicker than the average in the ty^e, but 

 on the other hand less knotty. In regard to structure and sporangia the plant in the main 

 agrees with the typical form. There seems, therefore, to be reason, at least at present, not 

 to consider f. dissita more than a form of A. Schmidtii. 



The present form of the species appears to grow in somewhat sheltered places. It is, 

 however, according to the label only kno^vn with certainty from the lagoon of Addu atoll 

 (25 fathoms). About this atoll Mr Stanley Gardiner remarks: "Its reef is perfect except 

 for two small passages to the north and two larger ones to the south. The lagoon has 

 a maximum of depth of 32 fathoms ; it is fairly open in the centre, but against the encircling 

 reefs has a perfect maze of coi'al heads, arising from 7 to 10 fathoms." The j)lant was sterile 

 when dredged in the middle of April, being however sparingly provided with overgrown 

 cavities of sporangia. 



Locality. The Maldives. Only one specimen with certainty known from the most southern 

 part of the Maldive group, viz. Addu atoll. Another and a younger one is perhaps from 

 Hulule, Male atoll, though possibly from some other atoll. 



Genus Lithothamnion Phil. (Fosl. emend.). 



2. L. fruticulosum (Kiitz.) Fosl. 



List of Lith. p. 6 (non Norw. Lith.); Spongites fruticulosa Kiitz. Polyp. Galcif. p. 33 

 et Tab. Phyc. 19, t. 99. Syn. L. fascicidatum /3. fruticulosum Hauck, Meeresalg. p. 274. 



f. clavulata Fosl. 



Corall. in Schmidt, Fl. Koh Chang, p. 17. 



f crassiuscula Fosl. (Plate XXIV. fig. 2). 



Corall. in Schmidt, Fl. Koh Chang, p. 17. 



Three small and rather delicate specimens of f clavulata from two localities coincide 

 with the specimens known from the Gulf of Siam. They also fully agree in habit and 



1 With regard to the limit of the genera I refer to " Revised Systematical Survey of the Melobesieae. " Trondhjem, 1900. 



