88 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



The specimens do not exceed 2 cm. in length, and occur on the stones bearing the 

 Lithothamnia ; but there is no reason to doubt that they belong to this species. 



Distribution. Also recorded from Cape Horn, Hermite Island, and Magellan Straits. 



PETROCELIS CRUENTA, J. Ag. Sp., ii. p. 490; Crouan, Fl. Finist.,p. 147, tab. 18, 

 f. 122. Scotia Bay, 9-10 fathoms. 



This species occurs on the stones bearing the Lithothamnia. Although it is not 

 in fructification, the absence of the zonate lines found in P. Middendorffii, Kjellm., and 

 the thin basal portion of the thallus indicate P. cruenta, J. Ag. 



Distribution. It does not appear to have been previously recorded from the 

 Antarctic Ocean. Known from Europe and North America. 



LlTHOTHAMNION LICHENOIDES, Heydr. f. ANTARCTICA, Fosl. ? List of Sp. (1898), 



p. 7 ; Svenska Exped. till Magell., Bd. iii. No. 4 (1900), p. 70. L. antarcticum, 

 Heydr. Lith. Mus. Paris (1901), p. 544. Scotia Bay, June 1903. 

 Distribution. Hermite Island, Falkland Islands, and Kerguelen. 



L. MAGELLANICUM, Foslie, f. CRENULATA, Fosl. in Kogl. Norske Vidensk. Selsk. 

 (1904), New Calcareous Algge, p. 3 ; op. cit., 1895, p. 8, fig. 8. Scotia Bay, 9-20 

 fathoms, July 1903. 



This plant is mixed with the two following on the same stones, but is the least 

 abundant of the three. It differs from the type in having a zonate margin and 

 irregular very shallow prominences on the surface, as in L.fecundum, but the surface 

 is less shining than in that species. 



LITHOPHYLLUM DiscoiBEUM, Foslie, f. ^QUABiLis, Fosl. in Kogl. Norske Vidensk. 

 Selsk. (1904), p. 3 ; Svenska Exped. till Magell, Bd. iii. No. 4 (1900), p. 73. Scotia 

 Bay, 9-10 fathoms. 



This plant has a smooth discoid thallus, with the immersed receptacles visible, only 

 when empty, as a number of circular depressions crowded on the central half of the 

 thallus. The margin is minutely cracked or fissured, as in L. incrustans, Fosl. 



L. DECIPIENS, Fosl. in Svenska Exped. till Magell., Bd. iii. No. 4 (1900), p. 71. 

 Scotia Bay, 9-10 fathoms. 



These specimens are in bad condition, all the sporangia being empty ; they are 

 crowded closely over the whole surface of the thallus, giving it a rough or minutely 

 reticulated appearance. 



Distribution. California and Fuegia. 



It is remarkable that L. rugosum, Fosl., which occurs with L. magellanicum and 

 L. discoideum on the coast of Patagonia, does not occur on any of the stones from the 

 South Orkneys. It is characterised by the prominent wart-like excrescences on the 

 thallus, like those of L. colliculosum Fosl., from which it differs in the character of 

 the sporangia. 



