39 



Stat. 93. Pulu Sanguisiapo, Tawi-Tawi Islands, Sulu Archipelago. 12 m. Lithothamnion 

 bottom. 



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



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



Stat. 109. Off Pulu Tongkil, Sulu Archipelago. 13 m. Lithothamnion bottom. 



Stat. 123. North Bay, Biaru Island. 36 — 27 m. Stonc and Lithothamnion bottom. 



Stat. 125. Off Sawan, Siau Island. 27 m. Stone and some Lithothamnion. 



Stat. 133. Lirung, Salibabu Island. Up to 36 m. Mud and hard sand. 



Stat. 169. Atjatuning, West coast of New-Guinea. Keef. 



Stat. 172. Gisser, anchorage between this island and Ceram-Laut. 18 m. Coral- and Litho- 

 thamnion bottom and Reef. 



Stat. 193. Sanana Bay, East coast of Sula Besi. Reef. 



Stat. 213. Saleyer and surroundings. Reef. 



Stat. 220. Pasir Pandjang, West coast of Binongka. Reef. 



Stat. 234. Nalahia Bay, Nusa-Laut Island. Reef. 



Stat. 240. Banda-anchorage. Lithothamnion-bank in 18 — 36 m. 



Stat. 250. Kilsuin, West-coast van Kur Island. 20 — 45 m. Coral and Lithothamnion. 



Stat. 261. Elat, West-coast of Great-Kei Island. Reef. 



Stat. 277. Kulewatti (Sollot) Bay, Dammer Island. Reef. 



Stat. 296. Noimini, South coast of Timor. Reef. 



Stat. 299. Buka- or Cyrus Bay, South coast of Rotti Island. 34 m. Mud, coral and Lithothamnion. 



Stat. 315. East of Sailus Besar, Paternoster Islands. Up to 36 m. Coral and Lithothamnion. 



A part of the type specimen of this species, from El Tor in the Red Sea, is represented 

 pi. V, hg. 1, and two other fragments from Obock in the Gulf of Aden pi. V, hg. 3 and 4. 



As formerly stated by myself, Sporolithon ptyekoides Heydr. is identic with the above 

 species. Sp. ptyekoides was at first divicled by Heydrich 1. c. into two forms, f. dttra and f. 

 mollis. Afterwards he considered f. dura as an independent species, the type of Sp. ptyekoides 

 in a more restricted sense than formerly. At the same time he divided f. mollis into two 

 separate species, which he named Sp. inollc and Sp. crassum, and the latter in its turn was 

 divided into two forms, f. typica and f. variabilis. From a comparison of the descriptions 1. c. 

 as well as the illustrations 1. c. pi. III, fig. 15 — 23, it will be realized that there is no real 

 distinction between the three species last named and A. erytkraeum, neither as regards habit 

 nor as to structure. The latter is a rather varying species, the habit of which often depends 

 on local conclitions and the shape of the substratum to which the plant is attached. Therefore, 

 I have classified only two forms, mainly in the same sense as they were first described by 

 Heydrich 1. c, viz. f. dura and f. mollis of which iragmentary but authentic specimens from 

 El Tor, clistributed by Heydrich himself, are represented pi. V, fig. 2 and pi. VI, fig. 1. 



The form dura is generally distinguisheel by thick and densely crowded branches (pi. V). 

 In f. mollis the branches frequently are thinner and less crowded than in the former (pi. VI). 

 Numerous transitions are, however, to be found, so that a certain limit can not be drawn. 

 Both forms partly grow gregariously, partly in different localities. 



As far as hitherto known, the species in question always attaches itself to some hard 

 object, corals, stones or other calcareous algae. Detached parts of the plant, however, seem to 

 continue their growth freely on the bottom, although apparently seldom. The plant sometimes 

 fully surrounds the object, especially when the latter is a small one. It partly develops excres- 

 cences or branches in a rather early stage, partly in a later stage and particularly when the 



