NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 291 



waii reveals no essential differences, as they fit well into the scale of vari- 

 ation. Finding no consistent means of distinguishing them, the type of 

 H. Marchantae is here considered to be a coarser form of H. nidifica and 

 one bearing stichidia in greater number. 



Recent collections in the Gulf have added greatly to the Hypnea as- 

 semblage known from that region, and a fine series of gradation types in 

 Hypnea nidifica is now on hand. Specimens quite identical with Hawaiian 

 forms are present and range into the coarser forms described as H. Mar- 

 chantae. Specimens from Costa Rica and from southern California have 

 been studied and should also undoubtedly be referred here. 



D. 342, 349, dredged in 22 m., Punta Penasco. Feb. ; D. 253, dredged 

 in 12-22 m., Puerto Refugio, Jan.; D. 469, in 30-36 m., Ensenada de San 

 Francisco near Guaymas, Feb.; D. 377, in 22 m., Tepoca Bay, Feb.; 

 D. 500, lower littoral rocks, Catalina Bay, near Guaymas, Feb. ; D. 607, 

 in shallow pools, San Gabriel Bay, Feb.; M. 48, cast ashore, Eureka, 

 May. 



Hypnea pannosa J. Ag. 



J. Agardh, 1847, p. 14; 1852, p. 453; Kutzing, Tab. Phyc. XVIII, tab. 

 27; Setch. & Gard., 1924, p. 758. 

 An examination of portions of the type material of this species from 

 Liebmann's original collection made at St. Augustine, on the west coast 

 of Mexico, confirms Setchell's conclusion that his Hypnea nidulans is dis- 

 tinct. The type of H. pannosa is that from which Kutzing drew his fig- 

 ures, but the statement that they are natural size is incorrect and mislead- 

 ing. The figures show the plants enlarged 1.5-2 diameters. The true H. 

 pannosa is therefore a much smaller plant than H. nidulans and more 

 compactly caespitose. Though most of the caespitose Hypneae of our col- 

 lections agree more properly with H. nidulans, at least one collection, D. 

 722, taken in July from the reef at Turner's Island, agrees well with the 

 type of H. pannosa. H. 651, dredged in 40 meters off San Jose del Cabo, is 

 similar in size and may be the same. 



Hypnea nidulans Setchell 



Setchell, 1924, p. 161 ; 1926, p. 100; Tanaka, 1941, p. 246, fig. 18. 



In recent years this species, originally described from Samoa, has been 

 recorded abundantly from many tropical Pacific stations. It is known 

 abundantly from Japan and now is found to be frequent in the Gulf of 

 California. One specimen in the Herbarium of the University of Califor- 

 nia from the Galapagos Archipelago seems also to be of this species. 



