NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 201 



GHLOROPHYGEAE* 



Family Ulvaceae 



Genus ULVA Linnaeus 

 Ulva dactylifera S. & G. 



Setch. & Gard., 1920, p. 272, pi. 21, fig. 1 ; 1924, p. 717. 



This species may be identified by its expanded, thick, laciniate fronds 

 composed of cells appearing vertically elongated in cross section. Thus 

 far, Ulva dactylifera has been collected only in warm waters in the Gulf 

 area: San Marcos Island, Tortuga Island, La Paz, Eureka, Espiritu 

 Santo Island. On the outer coast it is recorded from San Roque, near 

 Turtle Bay, and from exposed rocks, uppermost littoral in southern Cali- 

 fornia. The author's recent collections are of plants found growing on a 

 sandy substratum in warm oyster-culture pools at San Gabriel, Espiritu 

 Santo Island, D. 617, Feb. 



J. 11a, San Marcos Island, June; J. 31, Tortuga Island, June; 

 Brand. 9, 30, La Paz; M. 5, Eureka, May. 



Ulva angustata S. & G. 



Setch. & Gard., 1920, p. 264, pis. 22, 26, fig. 1. 



D. & R. 3152, on rocks between tide marks, 3292, on rocks in shallow 

 water, 3159, in tidal stream, near Guaymas, Dec. 



These specimens seem to agree in general with Setchell and Gardner's 

 concept of Ulva angustata. The cells are quadrate in cross section. The 

 fronds resemble those of Ulva teniata in form, but the lower parts are not 



*The general scheme of classification used is that found in Okamura, 1936, 

 pp. 1-5. He has employed the most modern systems, notably those of Kylin for the 

 Phaeophyceae and Rhodophyceae. 



Abbreviations used preceding numbers in the designation of collection data 

 are as follows: 



Brand.=collections of T. S. Brandegee of the California Academy of Sciences 

 Expedition to Lower California in 1890. 



M.=collections of Dr. and Mrs. Marchant, mostly at Eureka, south of La Paz, 

 and at Guaymas in 1917. 



J.=collections of Ivan Johnston, Expedition of the California Academy of 

 Sciences to the Gulf of California in 1921. 



H.=collections of John Thomas Howell of the Zaca Expedition of the Cali- 

 fornia Academy of Sciences to the Galapagos Archipelago in 1932. 



D. & R.=collections of Dr. Francis Drouet and Donald Richards of the Field 

 Museum Expedition to Sonora in the winter of 1939. 



D.^collections of the author during the }'ear 1940. All collection data for 

 these numbers are to be found in the Appendix. 



AHF=Allan Hancock Foundation type or isotype specimen to be found in the 

 Foundation Herbarium. 



