s M. FOSLIE, (Schwed. Südpolar-Exp. 



guishable from L. inagellaiiicum, and old specimens are in habit approacliing partly 

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

 mens of Lithoth. rugosum. 



Lithotli. gramdiferuin occurs in a depth of about 14 fathoms, sharing sub- 

 stratum with Lithoth. rugosum. Lithopli. discoideum, and L. decipiens, particularly 

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

 other. It is furnished with ripe sporangia in the middle of January. 



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



6. Lithothamnion rugosum Fosl. 



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



Syn. Lithothamnion glaciale Heydr. Lithoth. Mus. Paris (1901), p. 531;! 



As I have earlier often mentioned, several calcareous algïe, when the\' 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. rugosuiii. It was ori- 

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

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

 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 

 collection 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 Januar}-. 



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. Arlj. Heydr. tigoi), p. 27 (Note). 



