S M. FOSLIE, (Schwed. Südpolar-Exp. 



guishable from L. mageüaiiicnin, and old specimens are in habit approaching partly 

 old specimens of this species, growing on an uneven substratum, partly young speci- 

 mens of Lithoth. rugosuni. 



Litlioth. granuiiferuni occurs in a depth of about 14 fathoms, sharing sub- 

 stratum with Litliotli. rugosuni, Litlioph. discoideum, and L. decipieiis, particularly 

 the tvvo species last mentioned, two or three species often growing one over the 

 other. It is furnished w ith ripe sporangia in tlie middle of January. 



Area: Fuegia: The Observatory Island near the Staten Island (Skottsberg). 



6. Lithothamnion rugosum Fosl. 



Calc. Alg. Fuegia (1900), p. 66; tab. nostr. 1, fig. 12 — 15. 



Syn. Lithothamnion glaciale Heydr. Lithoth. Mus. Paris (1901), p. 539! 



As I have earlier often mentioned, several calcareous algie, when they are de- 

 veloped on a small substratum, will assume another shape than when they are grow- 

 ing on a larger one. This proves also to be the case with L. rugosum. It was ori- 

 ginally described as developing crusts somewhat cxpanding on stones, with more or 

 less crowded wartlike excrescences or short and simple branches. In the coUection 

 in hand, there are several specimens belonging to this species. They have all grown 

 round small pebbles, frequently i —2 cm. in diameter, developing now a feeble crust, 

 now a vigorous one, which sends forth short branches, either simple or once divided, 

 often of a more or less conical shape, or develops small lobes sending forth short 

 and rather anastomosing branches. 



As an extreme form of the species I now consider L. glaciale Heydr. 1. c. ' 

 It is a little coarser and develops more distinct lobes than any specimen in the 

 coUection in hand, but no doubt belongs to this series of forms. 



The species occurs partly in the litoral region (Desolation Island), partly in a 

 depth of 14 fathoms (Observatory Island). Its occurrence in other habitats is un- 

 known. Specimens with ripe sporangia have been taken in January. 



Area: Patagonia; Fuegia: Desolation Island, Puerto Angosto (DuSEN); Smyth 

 Channel, Chacabuco (v. Paessler); unknown locality (WILLEMS and ROUSSON); 

 Observatory Island near Staten Island (Skottsberg). 



' Cp. FoSLIE, Melob. Arb. Heydr. (1901), p. 27 (Nute). 



