4' 



rather seldom to occur. There are a rather great number of specimens in the Siboga collection, 

 but only a couple are provided with the said organs. The conceptacles are convex or subhemi- 

 spheric-conical, about 300 — 600 u. in diameter, when seen from the surface, but not sharply 

 defined. Externally they are rather like the corresponding organs in certain forms of Lithophyllu m, 

 but otherwise they come near to those in Goniolithon, as the carpospores arise from any part 

 of the conjugation cell. Sporangia are on the other hand common, and the sori are partly to 

 be found overgrown in great numbers by new formed tissue, partly, however, they are not to 

 be seen in a section. The sporangia are frequently 75 — 90 u.. long by a breadth of 35 — 55 f/.. 1 ). 

 Fertile specimens have been collected nearly all the year. 



Occurrence: Only one specimen has been brought home from each of the stations 

 4;, 109, 125, 133, 240, 296 and 311, a fact which seems to indicate that the species has been 

 scarce in these places. From the other stations are 2 — 8 specimens. It is uncertain whether the 

 plant forms banks at any of the quoted stations, alone or in company with other species, but 

 most probably it does not, as it is nearly always attached to other hard objects, but apparently 

 occurring both in the litoral and sublitoral regions. The species has also been met with at the 

 following places on the north coast of New-Guinea, here collected by Prof. A. Wichmann: 

 Pulu Adi; Pulu Kelamala, east of Pulu Adi; Anggar-Mios Island, Geelvink Bay; and Sari 

 (Sjari), west coast of Geelvink Bay 3 ). 



Area: Indic : The Red Sea ; the Gulf of Aden; the Maldives. 



2. Archaeolitliothamnion Siöogae A. Web. et Fosl. PI. VII. 



Three new Lithoth. p. 3. 



Stat. 86. üongala, Palos Bay, Celebes. Reef. 



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



Stat. 99. Off North-Ubian. 16 — 23 m. Lithothamnion bottom. 



This species is shrub-like or roundish, up to about 7 cm. in diameter. The thallus is 

 subdichotomously or irregularly branched, with axes of up to three orders. In typically developed 

 specimens the branch-systems issue in all directions from the centre of the thallus. The branches 

 are more or less spreading and curved, partly short, partly elongated and up to about 2 cm. 

 long, terete or slightly compressed, frequently knotty, with the ends rounded, 3 — 6, generally 

 4 — 5 mm. in diameter. I have not seen any attached specimens, but the plant is perhaps 

 attached at first to some hard object, although afterwards it detaches itself and lies free on 

 the bottom. However, a partly dead specimen in the collection is anastomosed with a roundish 

 extraneous object and apparently also fragments of another species, and besides it is burdened 

 with extraneous objects. New layers of tissue are here and there developed over the dead parts 

 of the plant, or partly stretched over the said objects as crustlike formations, from which short 

 branches are developed, such as in Lithothamnion pulcJirum and other species generally lying 



1) The measures of the sporangia in the species of this genus refer to the size of overgrown cavities due to the said organs. 

 The sporangia themselves are therefore in fact a little smaller. 



2) The Dutch New Guinea Expedition 1902 — 1903. 



SIBOGA-EXPED1T1E I.XI. 6 



