468 M. FOSLIE. 



sometimes approaches Lithophylluin congestum in habit, or even reminds one of L. platy- 

 phyllmn, while as remarked above the species in fact is most closely related to L. racemus 

 and L. Okamurai. 



This species seems to occur in the sublittoral zone, but it is unkno^vn to what depth 

 it descends. It is most frequently attached to corals, from which, however, it seems some- 

 times to loosen itself, or is freely developed at the bottom. The plant is sparingly provided 

 with reproductive organs in January. 



Locality. The Maldives : Hulule, Male atoll ; and the Laccadives : Minikoi atoll, quite 

 young and not certain. 



6. L. oncodes Heydr. 



Lithothamnion oncodes Heydr. in Bibl. Bot. 41, p. 6 ; and Ber. Deutsch. Bot. Ges. 1897, 

 p. 410. 



The species forms more or less thick and rather smooth crusts on rocks or corals. At 

 the Maldives as well as the Laccadives it appears partly in its typical, partly in a somewhat 

 varying form. The latter shows a rather uneven surface, which in the main depends on the 

 shape of the substratum, and in addition slightly differs in structure. On a cross section 

 the cells are here and there larger than is generally found, more regular, and with their longest 

 diameter in a vertical direction. These differences seem to me not to be of such importance 

 that they justify one in supposing it a separate species or form. 



The plant always appears to occur in the lower part of the littoral and uppermost part 

 of the sublittoral zone, scarcely descending deeper. It often grows in company with other 

 species, as Lithophyllum crcispedium and Goniolithon frutescens, and seems in some places to 

 be a rather important reef-builder. Specimens collected in the Maldives in January and in 

 the Laccadives towards the end of July are partly furnished with reproductive organs. 



Locality : the Maldives : Hulule, Male atoll ; and the Laccadives : Minikoi atoll. 



Genus Goniolithon Fosl. 



7. G. frutescens Fosl. 

 Calc. Alg. Funafuti, p. 9. 



f. typica (Plate XXV. fig. 4). 



f. congesta Fosl. mscr. (Plate XXV. fig. 5). 



Branches densely crowded and fastigiate. 



In the tj'pical form, as well as in f. Jlahellifurmis, the branches are rather irregular in 

 height and most often not densely crowded, reminding one in habit of the similar forms of 

 Lithophyllum moluccense. In f congesta on the other hand the plant forms hemispheric or 

 roundish balls up to 6 — 7 cm. in diameter, ynth densely crowded and on the whole strongly 

 fastigiate branches (Plate XXV. fig. 5). Besides, the branches frequently are thinner than 

 in the other forms, seldom more than 2 mm. thick. This fonn is very characteristic in its 

 typical shape, showing however numerous transitions to f. typica, although even in a young 

 state the branches are a little thiimer, with proportionally shorter axes than in the latter. 

 Plate XXV. fig. 6 shows a young sjiecimen of an intermediate form, which however comes 

 nearest to f. congesta. Typical specimens of f. flabelliforinis are not to be found in the 



