NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 267 



gans Foslie, 1895, including forma angulata and f. complanata, 

 p. 6, pi. 1, figs. 9, 10. Goniolithon (Cladolithon) elegans Foslie, 

 1899, p. 8. Lithophyllum elegans Foslie, 1909, p. 27; 1929, pi. 

 LXIII, figs. 1, 2. 

 Lemoine has given careful analysis of all of the habit and structural 

 features of this unique species, which has never yet been rediscovered. 

 From Lemoine's map of La Paz Bay, after Diguet's records, showing the 

 localities of the coralline banks, the "grisement" of L. Margaritae is indi- 

 cated lying off the outer shore of Isla San Juan Nepomucens, which itself 

 lies just off the lighthouse point a few miles north of the city of La Paz. 

 No other dredgings have been made in that vicinity, and apparently this 

 species is of limited distribution. Its remarkable habit and the now pre- 

 cisely identified type locality should make it readily recognized when 

 collections are again made in that region. 



Lithophyllum ? trichotomum (Heydr.) Lem. 

 Plate 55, Fig. 2; Plate 58, Figs. 1, 4-6; Plate 60 



Lemoine, 1929, p. 45. Lithothamnion ? trichotomum Heydrich, 1901, 

 p. 538. 



Examples of Diguet's type collection sent from the Museum of Paris 

 by Madame Lemoine are labeled: Lithothamnion trichotomum Heydr. 

 = Lithophyllum trichotomuin (Hey.) Lem. (le structure est celle des 

 Lithophyllum). These specimens have been compared with recent collec- 

 tions and found to match material from several localities. 



D. 425, in shallow lagoon at Pond Island, Feb.; D. 226, on rocky 

 shore of west side of Puerto Refugio, Jan.; D. 619, shallow water, San 

 Gabriel Bay, Espiritu Santo Island, Feb.; M. 15, Eureka, May. 



This plant resembles in habit Lithophyllum frutescens (Foslie) Lem. 

 (1911, p. 144) of the Indian and South Pacific oceans. 



Two types of conceptacles have been obsei-ved, but neither carpospores 

 nor tetrasporangia can be described. In D. 619 large superficial concep- 

 tacles which seem to be antheridial occur, 800 ix in external diameter, 

 broadly ovate conical with a single pore in the tip of the neck. In both 

 other collections large empty conceptacles have been found deeply em- 

 bedded and connected to the surface by a long canal. They are 450-500 jx 

 in diam. and occur in the broader portions of the fronds at the point of 

 junction of the branches. Externally these plants may be distinguished 

 from other known Pacific American species by their smooth, slender 

 branches and particularly by the truncate tips which usually appear as 

 white or light-colored "caps" to the branches. 



