WEBER-VAN BOSSE—MARINE ALG 
PryssonNELiA, Decaisne. 
Subgen. HuPryssonneELra, n. subg. 
Hypothallus filis arcte junctis, flabelli modo fusis, maxime erectis, 
1. PEYSSONNELIA COCCINEA, J. Ag. 
J. Agardh, Epicrisis Floridearum, 1896, p. 385. 
De Toni, Syll. Alg. vol. iv. sect. 1v. 1905, p. 1695. 
Seychelles, 31 fms. ; dry specimen. 
Saya de Malha, 55 fms. 
Distribution. West coast of Australia; Malay Archipelago. 
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The specimen is small and sterile; it was only by comparing it with “ Siboga ” material 
that I was able to name it. 
2. PEYSSONNELIA HARVEYANA(?), Crouan. (Plate 18. fig. 35.) 
Crouan in J. Agardh, Spec. Algarum, 11. 1852, p. 501. 
De Toni, Syll. Alg. vol. iv. sect. rv. 1905, p. 1694. 
Saya de Malha, 55 fms., on several dry, calcareous, little pebbles. 
Distribution. Coast of France, near Brest. 
The specimens are of a bright red colour and adhere firmly to the substratum; they 
approach both P. conchicola and P. Harveyana, but on account of the large cells of the 
hypothallus I feel inclined to regard them as P. Harveyana. With regard to distribution, 
it is more likely that they belong to P. conchicola, an inhabitant of the Red Sea. 
The specimens are all barren, and it is impossible to name them with certainty. 
3. PEYSSONNELIA CaLCcEA, Heydr. 
Heydrich, ‘‘ Neue Kalkalgen von Deutsch Neu-Guinea” in Biblioth. Bot. von Frank u. Luerssen 
1897, p. 10. 
Egmont, reef; in alcohol. 
Peros, Tle du Coin ; in alcohol. 
Distribution. Tami, near German New Guinea; Malay Archipelago. 
The specimens bear nemathecia with tetraspores. 
4, PEYSSONNELIA POLYMORPHA (Zan.), Schmitz. 
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Form GarpIneEri, n. f.—Thalio primo adherente, deinde a substrato soluto, tubera 
forma diversa, sed superficie levi formante, colore parum rubro cum siccatus est. 
Hypothallo cellulis longis 36-44-60 n, latis 8-10-16 ». Perithallo constante e 
seriebus cellularum sursum directarum, cellulis infimis majoribus, cellulis superiori- 
bus minoribus, longioribus aut brevioribus quam latis; latis 16-20-24 p. 
fructificationis ignotis. 
Amirante, 30, 45-60 fms. ; dry specimens. 
Organis 
The specimens from Amirante are nearly allied to P. polymorpha, but the loose thalli 
are smaller and the crusts are thinner than in the typical specimens of that species. The 
anatomical structure of the two algze is much alike, as far as the vegetative thallus is 
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