NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 327 



Laurenciae of the general L. paniculata type has been examined in the 

 University of California Herbarium, and they suggest strongly that we 

 are dealing with a variable group of perhaps several closely related enti- 

 ties which will require very careful study in nature before they become 

 understood. For the present I am inclined to let the Gulf plants remain 

 under the old name rather than to identify them erroneously with cer- 

 tain of the species found along the coast of California. 



Plants corresponding to Johnston's specimen determined as L. panicu- 

 lata by Setchell and Gardner in 1924 are the most abundant of the 

 species in the Gulf. Winter collections predominate by far, but most of 

 these are immature, indicating, perhaps, maximum development in spring. 



Plants here designated as L. paniculata are more robust than any 

 others except P. papulosa. They are easily distinguished from the latter 

 by obvious differences in the papillate branching. 



J. 30b, lower littoral rocks, San Francisquito Bay, June; J. 69, Isla 

 Partida, June; D. 234, cast up at Puerto Refugio, Jan.; D. 442, lower 

 littoral rocks, San Esteban Island, Feb. 



A number of other winter collections of immature plants which prob- 

 ably are of this species were made at Pond Island, Guaymas, Gonzaga, 

 Tiburon Island, and Agua Verde Bay. 



Laurencia papillosa var. pacifica S. & G. 



Setch. k Gard., 1924, p. 765, pi. 23, f^g. 18, pi. 24, fig. 34, pi. 43a-b, 

 pi. 54;Yamada, 1931, pi. 1. 



Specimens from at least three localities agree with the earlier collec- 

 tions of Johnston, Marchant, and Brandegee from the Gulf. They are 

 easily distinguished from other species of the region by their closely 

 crowded, wartlike lateral branches. The species is apparently a summer 

 annual, no mature plants being known from winter collections. It seems 

 to reach its maximum development in the southern part of the Gulf. 



J. 9, San Marcos Island, June; M. 38, Eureka, May; Brand., La 

 Paz; D. 663, rocky point 3 mi. north of Kino, July; D. 716, Turner's 

 Island, July; D. 601, San Gabriel, Espiritu Santo Island, Feb.; D. & R. 

 3399, Punta San Pedro, Guaymas, Dec. (young). 



Laurencia obtusluscula S. & G. 



Setch. & Gard., 1924, p. 760, pi. 23, fig. 17, pi. 55. L. obtusiuscula var. 

 corymbifera S. & G., 1924, p. 761, pi. 23, figs. 15, 16, pi. 45b. L. 

 obtusiuscula var. laxa S. & G., 1924, p. 762, pi. 29, fig. 67, pi. 

 52b. 



