8. Lithothamnion Dickiei Fosl. Fig. 13—14- 



New 



Lithothamnion polymorphum Dickie, Linn. Soc. Journ. Bot. Vol. XV, Pag. 452. 



Lithothamnion imbricatum Dickie, herb.; nee Zan. 



Island. 20 111. Coral and sand. 



Stat. Ni. 1'ulu Si Borneo-bank. 34 m. Coral bottom and Lithothamnion. 



With some doubt 1 ascribe a couple of specimens to this species. The plant is up to 

 the present unsuffkiently known, and its delimitation is vet hardly to be ascertained. Fig. 13 



exhibits a fairly entire specimen and 

 three fragments which are the types 

 of the species kept in the British 

 Museum. The former is about 7.5 

 by 5,5 cm. in diameter and about 

 2 cm. thick. It has perhaps been at 

 first attached to some hard object, 

 but has afterwards detachecl itself and 

 continuecl its growth freely at the 

 bottom. There are also a few frag- 

 ments kept in Kew Gardens herbarium. 

 In Suppl. Alg. Tahiti ') the plant is 

 mentioned as follows: "A calcareous 

 alga in rounded masses forming the 

 bottom in 1 o fathoms off Great Island 

 (Santa Cruz Major), Zambonga. The 

 dredge came up filled with these 

 masses". The thallus has a short mainstem which is either flattened and upwards broadening, 

 or very short and almost terete, and from which issue branch-systems repeatedly subflabellate 

 or irregular, spreading almost in one plane, one above the other. The branches, more or less 

 compressed, are about 1,5 or up to 2 mm. thick, and frequently much confluent with each 

 other. The tip of the branches are partly rounded, partly almost truncate. The specimens or 

 fragments examined are very scantily furnished with conceptacles of sporangia. The latter are 

 subprominent, flattened in the central parts, or occasionally almost clisc-shaped, though sometimes 

 not sharply defined, 350 — 400 u. in diameter when seen from above. The roof is intersected 

 with about 30 coarse muciferous canals. Sporangia are not known. 



From the scanty material hitherto known it is impossible to settle the clirections of 



variation vvithin the species. It seems, however, to come nearest to Lithothamnion eruèescens, 



next described, though less in liabit than in structure. When I first described the 



plant, I had reason to suppose that it was distinct from any other species then known. Nor did 



Fig. 13. Lithothamnion Dickiei Fosl. 

 The type specimens from Tahiti; .-/, seen a little from the side: nat. size. 



collected by II. X. MOSELEY of II.M.S. "Challenger", chierly obtained in Torre- Straits. Coasts 

 1 1. Bot. Vol. W. p. 43-'" 8. Algae collected "ii the Keef- of Tahiti. 9. Supplement to 



