36 



pi. X, fier. [o— ii, and Lithoth. Mald. and Laccad., fig. 5 — 6. Even in structure it somewhat 

 approaches the latter spreid especially as regards the shape and size of the cells of the medullary 

 hypothallium, luit the perithallic layer is differing. Thus heterocysts are missing which are 

 characteristic of Goniolithon. Besides in G. frutescens there is hut indistinct, if any, stratification 

 in the medullary hypothallium, vvhereas L. erubescens exhibits distinct hut often rather irregular 

 cup-shaped layers of tissue, and the consistency is looser in the former than in the latter. 

 Therefore, even stcrile specimens of both species are easily separated when closely examined. 

 Young specimens of L. erubescens may he confounded with young ones of other species, for inst. 

 Archaeolithothamnion timorense, especially however Lithothamnion australe. 



Occurrence: At stat. 303 the plant forms a large and extended bank in the lowest 

 part of the litoral and upper part of the sublitoral region, sparingly mingled with specimens of 

 Lithothamnion australe f. brachiata, Goniolithon Reinboldi and Lithophyllum Okamurai. perhaps 

 also other species (Fig. 1 — 2). lts occurrence here is recorded by Madame A. Weber-van Bosse 1 ). 

 At stat. 240 it seems also to have occurred in some number. On the other hand there are but 

 a few specimens from stat. 193, and a solitary and nut well developed specimen from each of 

 the stations 93 and 149. 



Area: North Pacific: Japan (Hinga), not certain ; Indic: Madagascar (f. madagascarensis); 

 South Atlantic: Chaloup Bay, Fernando do Xoronha, Brazil (f. americand)\ North Atlantic: 

 Bermuda (f. americana, t. prosiratd). 



10. Lithothamnion pulchrum A. Web. et Fosl. Fig. 18; PI. IV. 



Three new Lithoth. p. 3. 



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

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



The plant forms roundish shrubdike masses up to about 10 cm. in diameter. The branches, 

 issuing from a slightly thickened centre, are subdichotomously or irregularly divided, partly rather 

 spreading and somewhat curved, partly more crowded. often with rather long axes and side- 

 branches issuing at an almost right angle, terete or subcompressed, either cylindrical, or slightly 

 ing, or nöw and then slightly thickenins.;' towards the tip, with the ends rounded, 2 — 3, 

 frequently about 2,5 mm. in diameter. 



As remarked 1. c, the species seems mostly to develop itself freely at the bottom. 

 Among the gathered specimens I have found none that had developed itself attached to any 

 hard object. But when extraneous objects attach themselves to the plant, it develops a thin 

 crust and tends to cover the object (PI. IV, fig. 6). In the specimen here pictured a shell of 

 a mollusc is enclosed between the outermost branches. The shell is in part covered with a thin 

 crust issuiiiL; trom the branches that have been in contact with it. So also in the specimen 

 ted pi. IV, fig. 9. Here several branches have been covered with some lower animals, 



1. Études sur les Algues de 1. 'Archipel Malaisien. — Annales du Jardin Botanique de Buitenzorg. 

 1901, p. 132. — Cp. also the introduction of the present paper. 



