The following preliminary communications will on a subse- 

 quent occasion be followed by pictures. 



Lithothamnion californicum Fosl. mscr. 



The species forms 0.8 — 1.2 mm. thick, smooth and rather ex- 

 tended crusts on rocks between tides or on small stones in pools, 

 however, the shape of the crust depending on that of the substra- 

 tum. The conceptacles of sporangia are somewhat crowded espe- 

 cially in the central parts of the crust, subprominent, 300 — 100 p- 

 in diameter seen from above, almost disc-shaped, occasionally 

 slightly depressed in the central parts and here traversed by about 

 30 rather coarse muciferous canals. The sporangia are four-parted, 

 140—180 fi long and 60—90 fi broad. 



With regard to structure, the hypothallic layer is composed 

 of elongated cells partly with a rapid partly a rather slow con- 

 vergens towards matrix. The perithallic cells are square or rounded, 

 frequently 4 — 8 fi in diameter, sometimes with the longest diameter 

 in horizontal direction. 



The species approaches in habit partly Lithothamnion magel- 

 lanicum partly L. læve, but stands as regards structure nearest 

 to L. tenuissimum. 



It is hitherto only known from California, Point Fermin, San 

 Pedro, Setchell no. 1148, and Pacific Grove, Dr. Alton Saunders 

 no. 36 b. 



Lithophyllum africanum Fosl. mscr. 



f. truncata Fosl. mscr. 



L. proboscideum Fosl. On some Lith. p. 14; ex parte. 



f. intermedia Fosl. mscr. 



