43 



are developed over old and dead parts of the plant. This contributes to a more irregular 

 development, with branches more crowded, now and then anastomosing and thicker than 

 otherwise. The thallus is subdichotomously or irregularly branched, with axes of up to about 

 three orders. In specimens typically developed the branches issue in all directions from the 

 centre of the thallus. The branches are frequently rather spreading, partly fairly straight, partly 

 and more generallv curved, with side-branches which often issue at a rigdit or almost ribht 

 angle, and rather knotty especially in old specimens. They are terete or a little compressed, 

 either cylindrical or more frequently tapering, selclom slightly enlarged towards the tip, with 

 rounded ends, 1,5 — 2,5 mm. in diameter. 



A median section of a branch shows partly rather regular cup-shapecl layers of tissue, 

 such as in most branching species of the genus Lithothamnion, partly the said layers are not 

 to be seen, or very indistinct, such as in the other species of Archaeolithothamnion. The length 

 of the cells of the medullary hypothallium is frequently i'.\, — 2', times the breadth. They are 

 14 — 30 u.. long by a breadth of 7 — 14 u., most commonly however 16 — 22 u. long. The 

 perithallic cells are partly 7 — 12 u.. square, partly elongated and then as a rule somewhat 

 shorter than the hypothallic ones. Here and there ,appear irregularly alternating long and short 

 cells. Intermediate oblique cells 2 — 4 u.. in diameter, also in this species are present in a rather 

 large number particularly in the perithallic layer. 



Some of the specimens collected are provicled with sporangia, mostly, however, in small 

 number. The said organs are 70 — 90 p.. long and 35 — 50 u.. broad. Cystocarps and antheridia 

 are unknown. 



Among the species of this genus hitherto known, A. timorense is intermediate between 

 A. Sibogae and A. Schmidtii. On the other hand it is suggestive of certain forms of the 

 northern Lithothamnion tophiforme. Besides, sterile specimens are sometimes almost undis- 

 tinguishable from Lithothamnion pulchrum. Thus there are some from stat. 282, which partly 

 appear to belong to A. timorense (pi. VIII, fig. 2), partly come very near to L. pulchrum, 

 and are probably referable to the latter, although they are more densely branched, with shorter 

 axes than usually to be seen in this species. A few of them, on the other hand, partly approach 

 to A. Schmidtii, partly to delicate forms of A. Sibogae in habit. They cannot at present be 

 fixed with certainty. The most typically developed specimens of the species are from stat. 315, 

 but they are here in part rather burdened with extraneous objects (PI. VIII, fig. 1, 3, 4 — 6, 

 9 — 12, 14). Some of those from stat. 277 are a little coarser, and the branches are less 

 curved and less knotty (PI. VIII, fig. 7 — 8, 13). 



Occurrence: The plant seems to have been rather abundant at stat. 315, but 

 apparently scarce at stat. 277 as well as at stat. 282. From stat. 99 have been brought home 

 only a couple of specimens not quite typical, and from stat. 144 a single one. 



4. Are haeo lithothamnion Schmidtii Fosl. PI. VIII, fig. 15 — 17. 



Corall. in SCHMIDT, Fl. Koh. Chang, p. 16. 



Stat. 96. South-east side of Pearl-bank, Sulu Archipelago. 15 m. Lithothamnion bottom. 

 Stat. 169. Off Adjatuning, West-coast of New-Guinea. Reef. 



