[8 



The reproductive organs hitherto known are sporangia and cystocarps which occur on 

 different specimens. The tonner are subhemispheric, however now and then at length somewhat 

 flattened in Üic central parts, 500(400) — 700 ;/. in diameter, when seen from above. Tliey 

 are sometimes to be found overgrown by a new-formed layer of tissue extending itself over 

 the roof betere the Iatter gets dissolved. The sporangia are four-parted, about 140 — 160 by 

 60 — 80 •).. The conceptacles of cystocarps are conical, frequently low, but rather acute, 

 600(500) — 800 ■/.. in diameter when seen from the surface. The species is furnished with the 

 said organs, especially sporangia, in the months of January, February, June, November and 

 December, mostly however rather scantily. 



As to the relation to other species is to be observed that young specimens are rather 

 approaching to L. siamense\ but at an older stage the species is much differing from the 

 Iatter. It approaches nearly to L. fragilissimuiii, from which it sometimes is hardly distinguish- 

 able in a sterile stage, whereas on the other hand fertile specimens are easily recognized. In 

 habit it also comes near to certain forms of L. Engelhartii. On the other hand it is much 

 like L. funafutiense f. purpurascens^ particularly as regards the conceptacles of sporangia. 

 Although the material of the Iatter form is very scanty, I now suppose it ought to be considered 

 as a distinct species. 



Occur rence: There are only a couple of specimens from each of the stations above 

 quoted, from the station 125 even only a sterile and uncertain specimen. This fact seems to be 

 indicative that the species occurs but sparingly over a great part of the East-Indian Archipelago. 



A.rea: North Pacific: The Gulf of Siam. 



5. Lithothamnion prolifer Fosl. mscr. Fig. 8; PI. I, fig. 17 — 20. 



Thallus crustlike, irregularly extended, 0,5 — 1 mm. thick, scantily prolificating, with 

 irregular excrescences. Conceptacles of sporangia subprominent, at length rather flattened, 

 800 — 11 00 ij., in diameter. 



Stat. 78. Lumu-Lumu-shoal, Borneo-bank. 34 m. Coral and coralsand. 



Stat. 81. Pulu Sebangkatan, Borneo-bank. 34 m. Coral bottom and Lithothamnion. 



The plant forms irregular crusts on other calcareous algae, or different hard objects. The 

 crust is 0,5 — 1 mm. thick and of a hard consistency. In a young stage the plant clings to the 

 substratum and fairly conforms to it in shape, but afterwards it detaches itself little by little. 

 In the downwards turned detached part of the crust it is distinctly concentric zonate, partly 

 even forming rather deep striae, or furrowed. It is scantily prolificating, and besides it develops 

 irregular or short branchlike excrescences. The specimens in hand show several such excrescences, 

 which, however, are only owing to the form of the substratum or to foreign bodies having 

 attached themselves to the plant or its substratum, and then having been overgrown with 

 new-formed tissue. The excrescences seem to occur rather scarcely in typically developed 

 PI. I, tig. 19 — 20). The specimen pictured in pi. I, fig. 17 shows branchlike 

 formations which are apparently large and vigorous, still mainly owing their rise to the form 



